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Old 03-25-2021, 01:13 PM
ukvolvo ukvolvo is offline
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Join Date: Feb 2021
Location: Uk-North
Vehicle: 940 d24tic
Posts: 56
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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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