D24Tic 940 Turbo testing and intercooler questions
 

Hi Everyone,

I think my 940 is literally running no boost. It smokes a little on start but no other time so no tell tale failed turbo signs for such low performance.


That said, it is very dirty around the turbo area and caked.
So could the turbo be kaput but smoke free? It has years of grime on it to wash off.

Or are they really that slow standard and flat ? It does not feel boost assisted really. Acceleration increases at 3k but no noticeable kick at all or boost noise etc.

Should I run a t piece and test boost? What should it be if so?

The car has done 256k miles so far on standard everything major i suspect. Its got good service history but its soldiered on it seems beyond a water pump, thermostat and small bits.

The previous long term owner told me he had not cleaned the engine bay in 19 years and it shows

Also on the intercooler piping etc front and cooler itself, are they the same as petrol turbo units?

Thanks
Mick

Best to test it with a boost gauge as discussed below.

There is a moderate power increase felt that starts between 2500 - 3000 RPM, but not a neck-snapping explosion that you would feel in a modern hi-performance car. Sometimes I can hear the turbo whine on mine but not always. Depends on ambient conditions, and never when the radio is on. :p

Yes, good idea, and not hard to implement. Tee it into the small tubing running from the rear of the intake manifold to the boost diaphragm (the "flying saucer") on top of the injection pump. IIRC, D24T stock boost should be around 10 - 13 PSI, D24TIC may be higher.

You will want to get on the TB situation as addressed in your other post.

Sorry, IDK, not so familiar with the IC as unfortunately we didn't get the IC version here. :(

Thanks Buddy, Belts aa said in other post are top priority i know.

I have noticed the yellow pipe on the boost diaphragm goes to a sensor, is that a regulatory sensor like a n95 valve on other vw engines or mere boost low or high warning?

Mick

Not sure, can you post a photo?

I will get one today Thanks

As requested, pics of sensor :)

I should have took some more later, I really went at the engine bay today with some cleaner and it looks alot better. I can actually see hose ends and jubilee clips again haha

The boost compensator is the very tiptop of the injection pump. To measure turbo boost, you want to tee your gauge into the black tubing that I have circled in red.

With a long enough tube, you should be able to run it into the cabin so you can view it while driving. The engine will not generate much boost when not under load.

Attachment 1823

Well that looks very straight forward to tee off so i may well do it tomorrow night after work. What do you think i should be seeing on a tic, 14psi of boost peak ish?

What is the sensor attached to the yellow pipe on the blow off valve them? just overboost?

Mick

That is your EGR valve. The actuators connected to the other end of the yellow vac line are the control components for the EGR system.

You could disconnect that stuff if you want to. Usually doesn't work properly after 25+ years anyway, and these old engines have no feedback computer diagnostics to catch the malfunctions nor know if you have disabled it. EGR on an old diesel can add to intake manifold carbon deposits also.

You can do elaborate tests with vacuum gauges etc to determine whether the EGR system is still functioning as intended, but easier to eliminate it and head off any potential for problems. These old engines are not the cleanest runners regardless, and the EGR "system" (such as it is) is extremely primitive in its strategy even when working perfectly, so the emissions impact either way is negligible. :rolleyes:

At any rate it should not affect performance at all unless the EGR valve is sticking open or being commanded open at the wrong times. To answer your other question, no, none of this is related to control of turbo boost. On these engines the boost regulation is all fully mechanical and integral to the turbocharger. No external solenoids, N75 valve, etc like you were mentioning being familiar with a TDI engine. There are no electronics at all in terms of the turbo except for a switch mounted inside the overboost pressure relief valve on the front of the intake manifold, which gets tripped and lights up the turbo warning light on the dash if an overboost situation occurs (in case of wastegate failure etc).

All of the boost pressure control machinery should be visible on the turbo if you look over there, or post a picture of it and we can help identify. On our early style non-IC D24T engines here in the US, the wastegate actuator is internal so you can't see the vacuum bellows and actuator arm, but I think your D24TIC engine might have a proper external actuator that you would be able to see visually. IIRC they do also run higher boost, non-IC motor here is something like 10psi stock but I thought the D24TIC runs somewhere around 12-13.

Measuring boost pressure is a good idea certainly, but do note that if you are accustomed to newer direct injection electronically controlled diesels, like VW TDI, Peugeot, Ford, etc. The D24TIC Volvo engine has a very different feel and power curve, even when performing exactly as designed. D24T/IC is more smooth and progressive, and has a wider RPM range, but less absolute power. It runs more like a nice similar-size gasoline engine in terms of its power delivery, and quite unlike today's aggressively tuned diesels. So it may well be working normally, just not quite what you were expecting. This is a big heavy RWD car with an engine that was designed and marketed to achieve a balance of performance and fuel economy, not max performance (for that, Volvo had turbo gas engines available). They are good strong runners, especially at speed on the highway, and can feel peppy in city driving especially with the automatic transmission. But they don't really win drag races, smoke the tires off the line, etc, unless heavily modified.

It is not a "torque monster" type of engine, if that is the type of sensation you have in mind when you say "boost assisted". D24T and others from its era do not push you into the seat with a jolt of boost and torque at 1500 rpm and then run out of breath at 3000 rpm. The power comes on more gradually and is strongest ABOVE 2500 rpm. And they can continue to pull strongly up to 4000 rpm or higher. (And sound great when doing it) Part of what makes them in many ways more fun and involving than the newer direct injection diesels, which have more of an industrial type power characteristic. However, the modern ones obviously are far faster in terms of outright speed, just like today's gasoline cars versus those of the D24's era.

So, for us to be able to say if it's "too slow" or not, we need to know your context. If it feels slow compared to other similar type and age stock turbo diesel cars you have tried (eg large Mercedes turbodiesel from same time period), then there may be an issue. But if it feels slow to accelerate versus a 20 years newer Golf TDI or something like this, then it might just be the nature of the beast.

Oh BTW, in your second picture, the large rectangular relay very close to the EGR control solenoids is your glow plug relay. The one with "VOLVO" and "80A" and "12V" labeling on it.

Don't disconnect or remove that one, or the engine will no longer start. ;) Only the stuff above it, if you choose to.

The last car i am comparing it to is our v70 d5 so its got alot to live up to haha

I am a petrol man through and through but chose a diesel as its mpg is justified.

If i am honest i really need to test the car and see how she is boosting. It does not feel like the turbo kicks in at times and i suspect its mostly just the power curve that helps it pick up. Like i said testing definitely needed over speculation ey.

Is it worth blanking off the egr also? If so how do i do it.

If it is boosting right could i do anything at all to liven it up without pushing it? My Lovely lady calls it dangerously slow and misses the d5. I feel it's guttless at certain points too. Certainly does not keep up with modern traffic well.

I wanted it to have a bit more oophh as compared to the old 325tds i had it feels wofully slow.

I think with a good suspension set up and bushes it willl be a lovely fun car to drive

Thanks
Again
Mick

if this engine does deliver in a way that means it needs alot of revs i may consider long term using electronic boost regulation and a hybrid on standard boost. Our turbo may be very tired and in need of change anyway.


Would the fueling system adapt to this?The boost is measured by the pump if i am correct so hopefully it would.

That been said the standard turbo may be absolutely fine if worked harder I saw a rebuild kit on ebay for £25 yesterday haha no idea how you balance a shaft yourself although I have done jet engine parts so should be able to figure it out

Mick

Yes if you are comparing to a modern Volvo D5 with common rail direct injection and variable-vane turbo and twin cams and full electronic control, and around DOUBLE the max stock torque output at MUCH lower RPM, it's no surprise this engine may have a different dynamic feel even if it's all working as intended.

Volvo D5 maximum stock torque output: 440nm (325 lb-ft) at 1500 rpm
Volvo D24TIC maximum stock torque output: 250nm (184 lb-ft) at 2400 rpm

;) They are truly different animals and very much in different worlds in terms of performance and technology.

Turbo failure on a D24T is very rare. As in very, very, very rare. We basically never hear about it here. Most of these engines are running the stock original turbo still after almost 40 years and in some cases a half million miles or more. They pretty much just don't break unless run out of oil or if a failed air cleaner lets a bunch of dirt and sand in. So rebuilding the turbo is probably not the direction you want to be looking just yet.

Much, much more likely that either the engine is running as designed and just isn't on a par with what you are accustomed to, OR, turbo and/or fuel pump need adjustment. "Dangerously slow" and not able to keep up with traffic does sound like something might be off. Here where I live, highway traffic generally moves at 90 mph or more, and the engines in my old Volvos (even the lower tune non-IC D24T we have here) are perfectly happy to do 90-100 in order to stay with other vehicles. The only reason I don't do that is that the rest of the 40-year-old car containing the engine doesn't feel safe at those speeds. :p

If yours struggles to move with traffic then perhaps you have an issue with turbo output, or more probable, the injection pump timing is incorrect from a sloppily executed timing belt or IP replacement in the past.

Should start with measuring turbo boost as you have planned, and continuing the "Stage 0" maintenance you have already begun, focusing on a full and perfectly executed timing belt service (including water pump and thermostat) and ensuring all the fuel pump and transmission adjustment settings are spot on. Then later once everything is running as intended, you can certainly increase turbo boost and fueling settings above stock, as that can yield good further power increases and your car already having an intercooler is able to take advantage of more fuel and air quite easily. ASSUMING the cooling system is in healthy condition to safely exhaust the added waste heat from increased power. :cool:

Another way to check your car's performance: Could you find another antique Volvo turbodiesel to drive and compare yours to? Maybe meet forum member jpliddy and try out his car if he is not too far from you?

Ours was a 163 d5 so 250ft i thought ? Thats what ours is, soon to be was after clutch wear

And yeah i totally get it is a different drive as all classics are. I will run some tests but i definitely suspect it needs refining. I think a little more low down power and a little more oomph and I'll be happy.I could not imagine it EVER spinning the rear wheels in this current state except in ice haha

I have a cosworth t3 actuator in the workshop, looks similar so i wonder if its worth a swap. It has 13 psi stamped on it a free shaft and working spring mechanism if mine looks tired

Mick

And we are in Lockdown still buddy, If i drove a few hours away i would get a ticket haha

No I quoted the maximum listed for each engine, not knowing what generation D5 you have. Looks like the 163hp had either 340nm or 420nm depending on year. Still a huge difference and, what's more, coming on 1000rpm earlier and continuing for a long plateau across the rev range, unlike the single (higher) peak of the old engine.

We sadly never saw any D5 engine Volvos or any later diesels at all past 1986 here on these shores, so can only speculate on what one of them must feel like. :o But we did get many generations of VW/Audi TDI which are of much the same technology, DI, VNT, etc, to guess the probable difference in power delivery.

Your D24TIC should feel reasonably stout though, all that said, and easily driveable in traffic. Serious lack of power is not usually a complaint, except when compared against something with unfair advantages. :) Let us know what your check of turbo boost output and injection pump timing reveals.

Aha, well we should be that way here as well, but instead the bars and casinos are full, even while the schools are mostly closed down. :mad: :mad: :rolleyes:

Alot stricter here for longer hauls bud haha ,Risky for sure.

I will have to check the figures i found online as it's about 100 out haha

Either way i am not expecting a modern style. More powerful truck :cool:

The d5s actually drive like a petrol too, very long rev range for a diesel. Definitely more my thing coming from petrols.

The d24 appealed to me as its just such a brute of a old skool engine. Ive been offered a 3" exhaust for it. I imagine it would sound absolutely, diabolically ludicrous with one :D standard downpipe to 3" hahaha

And i shall report back after some tests :)

Mick

Disconnecting the EGR signal tubing and microswitches will render it inop. I took it a step further and removed the rest of the EGR valving and manifolding and installed blockoff plates for aesthetics and improved access. No noticeable performance difference.

Pretty close, yup. Doesn't quite need ice but it does take a certain skill to break it loose. :p

Well yes it is an old skool engine but in a different vein than the old stump pullers. Not much power or torque down low like the common stereotypical old skool diesel industrial engines; these like to rev more, smoother, quieter and less smoky.

You may want to study what the VW 4-cyl diesel gearhead crowd has done with their (similar bones) versions of these engines (the early pre-TDI versions). Much larger population; they have experimented more with VNT, porting, IP, manifold and exhaust mods., etc. ;)

I have another 2 restos to finish so no heavy modding haha I will just do my best to get her as nippy as possible :)

Had a experience this morning that summarised the way it drives well.

Let her run for 10 on the drive to warm but still cold so gently driving but briskly.

On my way and i get stuck behind a turnip crawling, then half way up a reasonably steep hill they pull in and make me brake. Literally from 5th to 2nd gear nothing at all no torque to be had and a huge que behind me as i try to get back up to speed. It literally crawled up to speed up a hill, surely that is not right? It is completely useless on anything beyond flat although alot nippier since my work once going.

I would not dare tow a kitten on rollerskates with this if thats all the torque they have

When cold its a nightmare as you cant use the revs to claw some power


Mick

That does sound much too slow. When running right, even stock, they are reasonably stout. Not fast, but easily able to get up to the speed of traffic with minimal drama.

Either a mis-adjusted injection pump or incorrect cam or IP timing, those would be my vote for most likely. Other common causes for "low power" would be restriction in the intake air, exhaust, or fuel supply, OR a turbocharger issue/failure as you mentioned. HOWEVER, with all of those, you would typically see the power loss be even worse at high RPM, when the engine would start to really choke on the lack of air/fuel flow.

In your case, it sounds like the opposite -- very weak at low RPM, but if you can get the revs up enough, it finally starts to pull a little better. Right?

So it's more probable that it is an engine tune issue for yours. Internal IP misadjustment, or incorrect injection pump static timing, or even external misadjustment of the throttle linkage causing the pump not to reach the full "throttle" setting even when the accelerator is floored. You could check last one that easily enough with a helper. The other checks will require a little more in-depth work.

VERY common with these engines is someone attempting to replace a timing belt or R&R the injection pump without the required special tools and methods, and then the timing is off as a result and majorly affects performance. So on your list of things to check, injection timing (using dial indictator) is near the top. ;) If that is confirmed within spec, then you would proceed to check turbo boost, and then finally to try adjusting the "smoke screw" on the pump and see if you can regain some power. But you only want to mess with those things after confirming correct base engine timing.

If injection timing is found to be wrong then that almost certainly means cam timing is also wrong. At that point you would want to just dig in for the whole timing belt refresh job since you say you plan on doing it anyway, and then continue with further diagnostics after that's done.

Do you ever see smoke from the exhaust? When and what color? How is the cold starting of the engine, easy, difficult, smoky, clean?

Yes they sound wonderful with the exhaust opened up. :cool:

Now define wonderful haha as in wonderful and sporty or ricer as you guys say with a 4" backbox loud haha. 3" is huge so its tempting but worrying.

And yes that sums her up well, flat low down. I need to get all the tools together and get setting up it seems. Still haven't tested boost yet as I've been so busy.

Excuse my ignorance but how could the cam timing be out? do you mean by one tooth for example on the belt? I know the ip pump is adjustable of course but i thought cam was fixed unless you like banana shaped valves.

I have found the how to videos confusing for these engines as they jump from cam to pump timing and I would much prefer to do each job separate.

Could you tell me the basic tools needed to do the timing belt, rear pump belt, pump timing and water pump buddy please? Does the injector pump need timing on the clock and in a different way also? like i said the videos for timing jump about a bit. The timing with a clock looks straight forward enough, as a toolmaker I've used it them plenty plenty.

Mick

940 TIC auto 1995
 

hi V8VOLVO i read middle paragraph with interest .saying misajustment of the THROTTLE LINKAGE .as my car after the throttle shaft leak seems to suffer this problem lack of power when accelerator is floored . you mention this can be checked with a helper ,what am i looking for and does engine need to be running , as revs could go to high for my ZF auto box
regards jim

Now let's don't overlook the questions v8volvo asked. Please answer. They are not joking around, but to help assemble clues to eventually leading us to the actual problem area. Unless you want to sit around benchracing talking about 3" exhaust all day. :rolleyes:



The camshaft pulleys are not keyed, allowing the camshaft to be clocked to infinite positions.

The same method I suggested in your thread "Cold Start"
https://www.d24t.com/showpost.php?p=14646&postcount=7

If you didn't understand it you should have mentioned it in that thread. Let's try not to derail ukvolvo's thread here too much. ;) We're already at 3 pages and nothing really achieved. :(

My goodness this engine is quirky, my Dad a mecanic of decades was speechless when I told him it's a morse taper pulley haha. A rant about german engineering followed

Yes agreed exhaust is way way down there priority wise. Never heard of bencracing before, sounds cheaper.

And the car behaviour wise.

Cold starts- Fires excellent once plugs warmed, Sometimes not a drop of smoke sometimes a bit on first start thats white/ blue which clears in 10 seconds maybe

It is not burning huge amounts as the dipstick has not moved in hundreds of miles so far.

I've been told it puts out just a little blue smoke at acceleration at times. When i left my friends drive he said it puffed just a smige on each gearchange/ throttle press as i pulled off slow. I went through 1st and 2nd very slow for what he saw

The main body of it seems good mechanically thankfully and its very likely the timing is out i bet knowing how they are set up now.

It did one unusual thing today. It only warmed up 30-40% on the gauge today after my commute so thermostat despite been done jn 2018 is another job whilst belts etc are done.

My apologies if i miss some questions, i am replying on a mobile mostly at work and typing is fun

I answered but didnt quote you bud sorry

It has used a 5-7 mm of dipstick in a few weeks doing daily runs totaling at least 500 miles.
Not too bad.


Mick

This morning was a cold damp morning. Car started first time but was a little rough for a minute and the car smoked for a minute maybe, Mainly clear white with hues of blue, but when i start her at work theres not a drop usually. I am keeping a super super close eye on water use as ive marked the tank. Hopefully it is merely condensation clearing and it is not using water. My drive is so uneven its hard to get a 100% same read every time.

Could the rough 30-60 seconds be valve stem oil seals and the excess thats dripped overnight burning off? Or injector rough ar start?

I will check every morning now as it usually smokes for a very brief spell blue and is fine.
Mick

Mick

After a vac pipe refresh there is a notable difference in low down power. Boost tests too follow to see if more leaks are present.

I am on with lifting the seats out as we speak to get the carpet out and diagnose this water ingress source

Mick

Vac pipe? :confused:

All the little boost and vacuum pipes on the inlet/ pump and to and from them have been done.

I had to use diesel spill pipe but it is used for it anyway. The original pipework was seriously shot and like garden watering leaky hose. You could rub it off onto your fingers and clearly see it splitting :(