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Old 03-24-2021, 05:59 AM
ukvolvo ukvolvo is offline
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Default Cylinder Head rebuild, Whats involved and how big a job?

I am thinking of taking the car off the road a few weeks and doing the whole head in one go as she uses oil (valve stem i would guess) and a little water.


Just how big a job is it? My old man is up for helping me out but im still curious if its a monumental job? Does the diesel pump stay attached or is it everything off?

I am questioning my sanity attempting this and need reassurance

Thanks
Mick
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Old 03-24-2021, 08:33 AM
v8volvo v8volvo is offline
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Nothing too out of the ordinary about it for the most part. It's a fairly standard design, overhead cam aluminum head. Easy for any machine shop to do the standard kind of work, replacing valves/valve guides/seals as needed, checking valve springs, checking head for warpage, and so on. The only tricky part is that if they need to flycut the head surface, the steel prechambers need to be removed and surfaced separately then reinstalled. And only a very tiny amount of material can be removed otherwise piston to valve clearance can be reduced dangerously. In short you don't really want to surface the head unless truly necessary, better to just clean it up carefully and reinstall.

As for the work of removing and replacing the head, again fairly straightforward, not necessarily a monumental job at least not compared to most other similar engines, though it is an involved process of course since you completely disassemble inlet, exhaust, two timing belts, and the diesel injection and electrical systems. The diesel IP can stay bolted to the block. The only unique task of the head R&R on a D24 type engine versus others is the timing process involved in getting the engine going again afterwards, and that's something I believe you have already been preparing for anyway. So, not really a big deal, especially if you are handy with internal engine work already. Just lots of wrenching and careful cleaning. And prayers for luck that you don't break off or strip any old fasteners, etc. That's where a simple job can get much more complicated and drawn out.

All that said, in regards to the sanity of it, a head R&R job is not something you would want to do just for fun. You would want to have a clear reason for it and goal that you are planning to address, as it is a fair amount of effort/time and parts expense for new headgasket, headbolts or studs, machine work cost, etc. Oil usage from valve guides/stem seals is not that common on these engines. Are you 1000% sure that is where the oil is going?

Any turbocharged diesel engine will (and should) consume a bit of oil, completely normal and no problem as long as it is not excessive. Up to 1 liter per 1000 miles is considered acceptable per VW guidance. If it is consuming any oil, the more common reason would be some ring/bore wear and a little blowby on a well used engine. Again, nothing to really worry about as long as it starts/runs well, doesn't have too filthy exhaust emissions, and oil use is within reason. You wouldn't want to do all the work of going through the head for the sake of limiting oil consumption and then find afterwards that there was no real change.

If it were me, I would try to trace the exact cause of the oil consumption before digging in deep. How much oil is visible in the turbo inlet tube near where the crankcase vent hose connects? And, what do you find if you do the catch can test? Disconnect that CCV hose, cap off the opening on the turbo inlet tube, and route the CCV hose from the valve cover instead into a temporary catch can under the hood (can needs to be vented so as to catch oil but not build up pressure, note!). Drive the car around for a few hundred miles and see how much oil accumulates in the can. If it is just a few drips, then you would suspect oil control rings, valve stem seals/guides, or turbo shaft seals as the culprit and could proceed with other tests to narrow down from there. If it's a notable amount in the can, though, then you just have some blowby as the cause.

Same thing with the coolant loss. Have you pressure tested the system and conclusively determined that all hoses, connections, radiator, heater core, expansion tank bottle, etc are free of leaks? What about the O-rings for the connections at the back of the cylinder head and block? Plastic fittings? Oil cooler?

Head gasket coolant leaks do occur on these engines, but usually they are combined with other very serious and obvious issues -- leakage of combustion gas into coolant and resulting aeration of coolant and overpressurization of the system, causing violent explosive coolant loss, bursting hoses, instant overheating under load, etc. If you are just having to add a bit of coolant but none of those other issues, I would look long and hard for other problems before suspecting a head or headgasket issue.

Bottom line, always worthwhile to do the troubleshooting work up front and be sure of exactly what you are going after, then proceed with a targeted repair for the particular problem you identified, rather than flying blind tearing apart areas of the engine that may have no issues and involve lots of work and cost.
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  #3  
Old 03-25-2021, 01:13 PM
ukvolvo ukvolvo is offline
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Originally Posted by v8volvo View Post
Nothing too out of the ordinary about it for the most part. It's a fairly standard design, overhead cam aluminum head. Easy for any machine shop to do the standard kind of work, replacing valves/valve guides/seals as needed, checking valve springs, checking head for warpage, and so on. The only tricky part is that if they need to flycut the head surface, the steel prechambers need to be removed and surfaced separately then reinstalled. And only a very tiny amount of material can be removed otherwise piston to valve clearance can be reduced dangerously. In short you don't really want to surface the head unless truly necessary, better to just clean it up carefully and reinstall.

As for the work of removing and replacing the head, again fairly straightforward, not necessarily a monumental job at least not compared to most other similar engines, though it is an involved process of course since you completely disassemble inlet, exhaust, two timing belts, and the diesel injection and electrical systems. The diesel IP can stay bolted to the block. The only unique task of the head R&R on a D24 type engine versus others is the timing process involved in getting the engine going again afterwards, and that's something I believe you have already been preparing for anyway. So, not really a big deal, especially if you are handy with internal engine work already. Just lots of wrenching and careful cleaning. And prayers for luck that you don't break off or strip any old fasteners, etc. That's where a simple job can get much more complicated and drawn out.

All that said, in regards to the sanity of it, a head R&R job is not something you would want to do just for fun. You would want to have a clear reason for it and goal that you are planning to address, as it is a fair amount of effort/time and parts expense for new headgasket, headbolts or studs, machine work cost, etc. Oil usage from valve guides/stem seals is not that common on these engines. Are you 1000% sure that is where the oil is going?

Any turbocharged diesel engine will (and should) consume a bit of oil, completely normal and no problem as long as it is not excessive. Up to 1 liter per 1000 miles is considered acceptable per VW guidance. If it is consuming any oil, the more common reason would be some ring/bore wear and a little blowby on a well used engine. Again, nothing to really worry about as long as it starts/runs well, doesn't have too filthy exhaust emissions, and oil use is within reason. You wouldn't want to do all the work of going through the head for the sake of limiting oil consumption and then find afterwards that there was no real change.

If it were me, I would try to trace the exact cause of the oil consumption before digging in deep. How much oil is visible in the turbo inlet tube near where the crankcase vent hose connects? And, what do you find if you do the catch can test? Disconnect that CCV hose, cap off the opening on the turbo inlet tube, and route the CCV hose from the valve cover instead into a temporary catch can under the hood (can needs to be vented so as to catch oil but not build up pressure, note!). Drive the car around for a few hundred miles and see how much oil accumulates in the can. If it is just a few drips, then you would suspect oil control rings, valve stem seals/guides, or turbo shaft seals as the culprit and could proceed with other tests to narrow down from there. If it's a notable amount in the can, though, then you just have some blowby as the cause.

Same thing with the coolant loss. Have you pressure tested the system and conclusively determined that all hoses, connections, radiator, heater core, expansion tank bottle, etc are free of leaks? What about the O-rings for the connections at the back of the cylinder head and block? Plastic fittings? Oil cooler?

Head gasket coolant leaks do occur on these engines, but usually they are combined with other very serious and obvious issues -- leakage of combustion gas into coolant and resulting aeration of coolant and overpressurization of the system, causing violent explosive coolant loss, bursting hoses, instant overheating under load, etc. If you are just having to add a bit of coolant but none of those other issues, I would look long and hard for other problems before suspecting a head or headgasket issue.

Bottom line, always worthwhile to do the troubleshooting work up front and be sure of exactly what you are going after, then proceed with a targeted repair for the particular problem you identified, rather than flying blind tearing apart areas of the engine that may have no issues and involve lots of work and cost.
Some good advice buddy.

The whole reason i wanted to do the head was suspected valve stem oil seals and noisy tappets. The rationale behind thinking it is using oil due to stems is the cold starts. When the vehicle has stood for longer periods it starts rougher for a few seconds and throws out more blue smoke. Start it after a shorter stand say a shift at work (8hrs) and she starts beautiful with nothing more than the max fuel start grey haze.

In the past i had usually seen this in engines with failed stem seals as the oil drips into the bores over night and burns off at start up. I am watching oil use closely and have recorded mileage at last top up so we will see how fast she goes through the dipstick. I have used a full top up bottle since oil change but did not record the mileage accurately enough so have to test again.

On the water front i may well be dealing with heater matrix so the head thankfully is less likely. I am getting wet carpets below and have been using tissue to test the color as there was a cut in the carpet already (somebody knew and hid a problem surprise surprise). The carpet was not wet above but i was just poking around the car and noticed the hole. On inspection i initially assumed it was the sunroof to blame having been done 2 years ago at volvo.

It is always brownish not blue, but the person i got it from said he had the same symptoms on a petrol and thinks the insulation changes its color. So i suspect now it may well be heater core. Carpets out is first port of call and a uv leak additive in. Hopefully it will clearly show dripping under uv in the bay or under the dash. Another fun job no less.

As regards the breather system, Are you suggesting in affect fitting a oil catch tank for a extended period to see how much oil is in the breather system? I can do that most certainly too, yummy fumes. Reminds me of my old fiat 500 i had at 17, that stunk of fumes with the induction kit i made venting to atmosphere haha

This car is really testing our love for her haha

The reality is i want the car mechanically as good as she can be so i can consider options like a vnt and not worry about damage to the motor. I don't want to exceed standard boost etc but want to create more drivable power. Who knows maybe the car will be different all together once timed correctly etc and it wont need it.

Mick
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Old 03-25-2021, 09:30 PM
ngoma ngoma is offline
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Another telltale heater core leak clue: Front windshield likes to fog up at startup after sitting a while, enough time for sufficient leaking coolant to vaporize on the surface of the heater core as it heats up and steam up the windshield.

However--- the #1 reason by far for wet carpets up front is leaking blockoff covers over the vestegial foot vents behind the plastic kick panels. By far.

Open up the kick panels, pour a good quantity of water into the windshield cowl louvers, and watch with a strong light for the small rivulets of water emerging from the corners of the rounded square plastic blockoff plugs. Clean well with brush and detergent rag, dry, and seal it up with good body seam sealer or butyl caulking, or contractors grade caulking. Silicone caulk or most other water-based products don't seam to stick well over time.

Second (or third) most common reason for wet front carpets (in competition with clogged sunroof drain tubes) is mis-positioned baffle diverter cover over the wiper motor under the windshield cowl. Allows water to enter thru the HVAC fan housing, and will also degrade the lower fan motor bearing. This will drain into that side footwell only.

Other places to look for leaking coolant, in descending order:

1. Heater flange o-ring seals at (1.) rear of cylinder head and (2.) rear of engine block (mentioned above). You will see coolant dripping off the bellhousing.

2. Leaky hoses anywhere, could be pinholes or seeping thru clamped areas.

3. Heater core or Radiator.

4. Head gasket (external leak) look under the vacuum pump for the most common location.

5. Plastic drain tee above the oil pressure sensor/motor mount bracket area.

Some of these coolant leaks I believe are self-induced as Volvo fitted a higher pressure coolant cap as a standard "feature," overly stressing especially the heater core and radiator. The black ones (75 kPa?) are safer.
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  #5  
Old 03-27-2021, 10:36 AM
v8volvo v8volvo is offline
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Quote:
Originally Posted by ukvolvo View Post
reason i wanted to do the head was suspected valve stem oil seals and noisy tappets. The rationale behind thinking it is using oil due to stems is the cold starts. When the vehicle has stood for longer periods it starts rougher for a few seconds and throws out more blue smoke. Start it after a shorter stand say a shift at work (8hrs) and she starts beautiful with nothing more than the max fuel start grey haze.

In the past i had usually seen this in engines with failed stem seals as the oil drips into the bores over night and burns off at start up. I am watching oil use closely and have recorded mileage at last top up so we will see how fast she goes through the dipstick. I have used a full top up bottle since oil change but did not record the mileage accurately enough so have to test again.
If in fact the valve stem seals and tappets are problematic, those both could be replaced with the cylinder head remaining installed on the engine, assuming you are working carefully with the right equipment. Noisy tappets especially are very easy to replace if you are already doing a timing belt job, just pop the cam out (carefully, using correct sequence on the cam bearing caps), replace 12 lifters, then reassemble with new cam seals. Valve stem seals is much more involved, requiring compressed air to keep the valves closed while springs/keepers/retainers are removed, and a special fixture to compress the valve springs with the head installed on the engine. But certainly doable and a common procedure, everything available for it.

Again, though, serious oil usage from valve guides and valve stem seals is highly unusual on these engines. AND, if the smoke you are seeing is indeed caused by leakage down the valve stems, you would definitely see it after standing 8 hours at work just as much as you would after standing overnight, 8hrs is plenty of time for oil to leak down the stems IF that is what is in fact occurring.

Much more likely, the smoke you're seeing after overnight starts is not smoke from engine lube oil, but rather from incompletely combusted diesel fuel oil in a colder engine after weathering the lower overnight low temp than what the engine sees while sitting at work during daytime temps. That blue fuel smoke would be typically caused by any combination of: 1) incorrect injection/cam timing, 2) one or more dead glow plugs, 3) incorrectly or non-functioning cold start timing advance system, 4) slightly down on compression, or 5) injectors a little tired and spray patterns not 100%. Easiest/likeliest and first things to check would be the timing and the glow system.

Diesel fuel smoke can be blue, white, grey, in addition to the black, depending on the situation and the cause. Blue smoke in a gas engine is surefire sign of engine oil consumption but not necessarily so in a diesel. Blue smoke specifically only upon startup in a gas engine furthermore is a sure sign of valve stem seals/guides in trouble. So all of your logic is totally correct on a gas engine, but on an old diesel, it's quite different. Especially in the absence of massive oil consumption, I would put valve stem seals way, way down at the bottom of the list for potential causes of the smoke you have seen, after investigating the fuel/glow/timing areas first. Yes, valve guides/stems "possible", but just not a pattern that is often seen.

In general also, a little blue/white haze from fuel for the first minute or two after a morning cold start is quite normal and acceptable.

All that said, if the tappets are noisy, then that IS something you would be for sure right to investigate. We never got hydraulic tappet D24Ts here in the US but the similar relative 4/5 cylinder VW/Audi diesel (and gas) engines with the identical hydro lifters can have the lifters fail and make noise. And in fact just recently I went through this myself when my junker VW TDI with these same lifters experienced a serious failure that could just as easily happen on a D24 type engine. So yes good to check that out, and if it is definitely tappet noise, make repairs proactively.

Did you try the trick of disabling the vacuum pump to make sure it's not the source of the noise you are hearing, rather than tappet noise? And the trick of killing injectors one by one to make sure it's not a ticking/knocking injector? Note, in a gas engine lifter/tappet ticking is easy to identify since there is nothing else in that part of the engine that can sound that way.... but in the clatter environment of a diesel engine it can be hard to tell the different types of noise apart, and similar noises can come from different components, so organized troubleshooting by process of elimination is time well spent.

Tappets can also be checked individually for excess play using a soft plastic tool depressing them when unloaded. Should only be able to move fractionally and all should sit at the same height out of the head when not depressed.

Quote:
Originally Posted by ukvolvo View Post
As regards the breather system, Are you suggesting in affect fitting a oil catch tank for a extended period to see how much oil is in the breather system? I can do that most certainly too, yummy fumes.
Yes exactly that would be the method. Temporary, so the fumes would probably not be too bad to tolerate for a few days, and they are much less stinky in a diesel versus a gasser anyway.

I would put it in place just like you're saying, run the car for a few hundred miles, and see what the accumulated oil quantity is.

But that's only necessary if you think oil consumption rate is high and you're searching for the cause. Even easier, first, would be to just keep track of how much you're actually putting in without making any further changes, as you were already planning. If it's only using a liter between oil changes, then that's not much, and maybe not worth your attention.

Quote:
Originally Posted by ukvolvo View Post
The reality is i want the car mechanically as good as she can be so i can consider options like a vnt and not worry about damage to the motor. I don't want to exceed standard boost etc but want to create more drivable power. Who knows maybe the car will be different all together once timed correctly etc and it wont need it.
All sounds like a good plan, always nice to start with something that you know is squared away on all the basics first and a good platform for upgrades! Plus, you are also right that once you have got a good "Stage 0" fully dialed in, you may find it already much improved and more satisfying even after those steps alone.
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  #6  
Old 03-28-2021, 12:27 AM
jpliddy jpliddy is offline
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hi is this a option to help find where noise is coming from . disconnect the thin white hose at the bulkhead T joint if you have a noisy vacuum pump the noise stops but make sure to connect it back up as your servo vacuum will not work your BRAKES only a thought as there can be a few noises going on ie alternator can be a distraction noise too . i use a cheap mechanic stetestcope too seems to help .
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Old 04-05-2021, 12:34 PM
ukvolvo ukvolvo is offline
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Quote:
Originally Posted by jpliddy View Post
hi is this a option to help find where noise is coming from . disconnect the thin white hose at the bulkhead T joint if you have a noisy vacuum pump the noise stops but make sure to connect it back up as your servo vacuum will not work your BRAKES only a thought as there can be a few noises going on ie alternator can be a distraction noise too . i use a cheap mechanic stetestcope too seems to help .
I will give it a try thanks. I definitely need a stethoscope .

Mick
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Old 04-05-2021, 12:37 PM
ukvolvo ukvolvo is offline
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Quote:
Originally Posted by v8volvo View Post
If in fact the valve stem seals and tappets are problematic, those both could be replaced with the cylinder head remaining installed on the engine, assuming you are working carefully with the right equipment. Noisy tappets especially are very easy to replace if you are already doing a timing belt job, just pop the cam out (carefully, using correct sequence on the cam bearing caps), replace 12 lifters, then reassemble with new cam seals. Valve stem seals is much more involved, requiring compressed air to keep the valves closed while springs/keepers/retainers are removed, and a special fixture to compress the valve springs with the head installed on the engine. But certainly doable and a common procedure, everything available for it.

Again, though, serious oil usage from valve guides and valve stem seals is highly unusual on these engines. AND, if the smoke you are seeing is indeed caused by leakage down the valve stems, you would definitely see it after standing 8 hours at work just as much as you would after standing overnight, 8hrs is plenty of time for oil to leak down the stems IF that is what is in fact occurring.

Much more likely, the smoke you're seeing after overnight starts is not smoke from engine lube oil, but rather from incompletely combusted diesel fuel oil in a colder engine after weathering the lower overnight low temp than what the engine sees while sitting at work during daytime temps. That blue fuel smoke would be typically caused by any combination of: 1) incorrect injection/cam timing, 2) one or more dead glow plugs, 3) incorrectly or non-functioning cold start timing advance system, 4) slightly down on compression, or 5) injectors a little tired and spray patterns not 100%. Easiest/likeliest and first things to check would be the timing and the glow system.

Diesel fuel smoke can be blue, white, grey, in addition to the black, depending on the situation and the cause. Blue smoke in a gas engine is surefire sign of engine oil consumption but not necessarily so in a diesel. Blue smoke specifically only upon startup in a gas engine furthermore is a sure sign of valve stem seals/guides in trouble. So all of your logic is totally correct on a gas engine, but on an old diesel, it's quite different. Especially in the absence of massive oil consumption, I would put valve stem seals way, way down at the bottom of the list for potential causes of the smoke you have seen, after investigating the fuel/glow/timing areas first. Yes, valve guides/stems "possible", but just not a pattern that is often seen.

In general also, a little blue/white haze from fuel for the first minute or two after a morning cold start is quite normal and acceptable.

All that said, if the tappets are noisy, then that IS something you would be for sure right to investigate. We never got hydraulic tappet D24Ts here in the US but the similar relative 4/5 cylinder VW/Audi diesel (and gas) engines with the identical hydro lifters can have the lifters fail and make noise. And in fact just recently I went through this myself when my junker VW TDI with these same lifters experienced a serious failure that could just as easily happen on a D24 type engine. So yes good to check that out, and if it is definitely tappet noise, make repairs proactively.

Did you try the trick of disabling the vacuum pump to make sure it's not the source of the noise you are hearing, rather than tappet noise? And the trick of killing injectors one by one to make sure it's not a ticking/knocking injector? Note, in a gas engine lifter/tappet ticking is easy to identify since there is nothing else in that part of the engine that can sound that way.... but in the clatter environment of a diesel engine it can be hard to tell the different types of noise apart, and similar noises can come from different components, so organized troubleshooting by process of elimination is time well spent.

Tappets can also be checked individually for excess play using a soft plastic tool depressing them when unloaded. Should only be able to move fractionally and all should sit at the same height out of the head when not depressed.



Yes exactly that would be the method. Temporary, so the fumes would probably not be too bad to tolerate for a few days, and they are much less stinky in a diesel versus a gasser anyway.

I would put it in place just like you're saying, run the car for a few hundred miles, and see what the accumulated oil quantity is.

But that's only necessary if you think oil consumption rate is high and you're searching for the cause. Even easier, first, would be to just keep track of how much you're actually putting in without making any further changes, as you were already planning. If it's only using a liter between oil changes, then that's not much, and maybe not worth your attention.



All sounds like a good plan, always nice to start with something that you know is squared away on all the basics first and a good platform for upgrades! Plus, you are also right that once you have got a good "Stage 0" fully dialed in, you may find it already much improved and more satisfying even after those steps alone.
I am working my socks off at the moment so have no got alot done physically. She has been running fine albeit using a little water and im checking oil use up to 1000k.

I have changed all the vacuum pipes on inlet etc as they were very poor condition and hope it makes a difference next time i drive her. No miracles on test drive but a definite improvement. On the work run i will see if it performs different on familiar hills etc.

Still building towards the t belt as main goal. I got a cam belt for £6.50 haha no bargains on the rest yet,

Mick

Last edited by ukvolvo; 04-05-2021 at 12:41 PM.
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