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Old 08-11-2021, 04:37 PM
Sethsquatch Sethsquatch is offline
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Default Pinzgauer oil in coolant.

Have been driving my pinzgauer 718 p90 incrementally, working out bugs and such, and recently tried taking it on a trip.
45 mins into the trip, temp climbed and touched the red, I pulled over immediately and as I did, a hose burst, leaking what should have been coolant everywhere, but instead started with what seemed like a couple quarts of oil.
The oil cooler is/was brand new, the radiator is upgraded aluminum unit, it has a new turbo, new head gasket as well.
My question is, is there another place somewhere in the engine or cooling system where oil could mix with coolant? All research I have done points to the oil cooler, but seems iffy since it's brand new.
Any input is appreciated, thank you!
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Old 08-11-2021, 06:41 PM
v8volvo v8volvo is offline
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Bummer, sorry to hear.

Most likely would be head gasket. All the symptoms you described point to a progressive head gasket failure. The HG would have begun to leak and allow cylinder combustion pressure into the cooling system, causing pressures to spike dramatically and aerate the coolant causing the sudden overheating of the engine, and oil leaked into the coolant at the same time. Then once you're starting to get combustion gases into the coolant while still running the engine with a load, you get into a feedback cycle where the engine is getting rapidly hotter and hotter, that makes the HG fail worse and worse, more and more gases and oil go into coolant, the cooling gets even less effective and the engine heats up even more, and so on, until you pull over and shut it down.

Note that you said the hose burst after the engine overheated so the hose failure was a result of the overheating, not the cause.

Guessing you were headed up I-70 when this happened or climbing some other long steep hill on a warm August day?

Could be something else, but not very likely given the situation you saw. Oil cooler failure could introduce oil into the coolant also, but it would not result in overheating, at least not sudden overheating.

On a freshly overhauled engine like yours, headgasket failure in a short time would most likely be from one (or more) of these 3 causes:
- injection and/or cam timing not set correctly, resulting in excessive cylinder pressures
- cylinder head bolts not torqued correctly or not retorqued, or if studs were used, incorrect torque procedure or lubricant etc, OR using a clicker-type torque wrench for installation rather than a strain gauge or beam type wrench
- cylinder head warped or incorrectly machined during overhaul or insufficient surface preparation

Any built in vulnerabilities like these can be hidden when cruising around town but will be uncovered the first time the engine sees a sustained hard load in warm weather. With a heavy Pinz in the Rocky Mountains in the summertime, the stakes for engine and cooling system perfection are high.

The headgasket failure can be confirmed with the "bubble test" or a block test to check for hydrocarbons in the coolant. You can also do a pressure test of the cooling system after replacing that hose but be careful as this can forced coolant into the cylinders if the HG is indeed failed, and result in hydraulic lock and bent connecting rods/cracked pistons if you attempt to start the engine afterwards.
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Old 08-11-2021, 06:55 PM
Sethsquatch Sethsquatch is offline
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Well this is the type of know how I came to hear, although terrible news!
My mechanic did replace the hose and said he pressure tested the system and it held pressure, but I'll let him know about pushing coolant into the cylinders. I could have been wrong about the hose bursting after, it just seemed that way.
Thanks so much for the detailed write up!






Quote:
Originally Posted by v8volvo View Post
Bummer, sorry to hear.

Most likely would be head gasket. All the symptoms you described point to a progressive head gasket failure. The HG would have begun to leak and allow cylinder combustion pressure into the cooling system, causing pressures to spike dramatically and aerate the coolant causing the sudden overheating of the engine, and oil leaked into the coolant at the same time. Then once you're starting to get combustion gases into the coolant while still running the engine with a load, you get into a feedback cycle where the engine is getting rapidly hotter and hotter, that makes the HG fail worse and worse, more and more gases and oil go into coolant, the cooling gets even less effective and the engine heats up even more, and so on, until you pull over and shut it down.

Note that you said the hose burst after the engine overheated so the hose failure was a result of the overheating, not the cause.

Guessing you were headed up I-70 when this happened or climbing some other long steep hill on a warm August day?

Could be something else, but not very likely given the situation you saw. Oil cooler failure could introduce oil into the coolant also, but it would not result in overheating, at least not sudden overheating.

On a freshly overhauled engine like yours, headgasket failure in a short time would most likely be from one (or more) of these 3 causes:
- injection and/or cam timing not set correctly, resulting in excessive cylinder pressures
- cylinder head bolts not torqued correctly or not retorqued, or if studs were used, incorrect torque procedure or lubricant etc, OR using a clicker-type torque wrench for installation rather than a strain gauge or beam type wrench
- cylinder head warped or incorrectly machined during overhaul or insufficient surface preparation

Any built in vulnerabilities like these can be hidden when cruising around town but will be uncovered the first time the engine sees a sustained hard load in warm weather. With a heavy Pinz in the Rocky Mountains in the summertime, the stakes for engine and cooling system perfection are high.

The headgasket failure can be confirmed with the "bubble test" or a block test to check for hydrocarbons in the coolant. You can also do a pressure test of the cooling system after replacing that hose but be careful as this can forced coolant into the cylinders if the HG is indeed failed, and result in hydraulic lock and bent connecting rods/cracked pistons if you attempt to start the engine afterwards.
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Old 08-12-2021, 12:04 PM
ngoma ngoma is offline
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Curious to know if there is any external oil or coolant leakage at the HG under the vacuum pump area. Overheat/HG problem often leads to external leaks in this area. Maybe not enough time run to verify leakage but it could be a sign.

Quote:
Originally Posted by v8volvo View Post
Guessing you were headed up I-70 when this happened or climbing some other long steep hill on a warm August day?
I heard I-70 is closed due to excessive eroded soil on roadway from recent fires?
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  #5  
Old 08-12-2021, 10:52 PM
Sethsquatch Sethsquatch is offline
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Quote:
Originally Posted by ngoma View Post
Curious to know if there is any external oil or coolant leakage at the HG under the vacuum pump area. Overheat/HG problem often leads to external leaks in this area. Maybe not enough time run to verify leakage but it could be a sign.


I heard I-70 is closed due to excessive eroded soil on roadway from recent fires?
I will have mechanic check for that, he is putting UV dye in oil to trace the leak.

Yeah I70 is shut down for days no. Wildfires from last year = no vegetation to stop soil from creating mudslides. It's been a goat roping, traffic re-routed on 4+ hour detours through mountain towns. Should be open in the next couple days tho!
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  #6  
Old 08-13-2021, 09:31 AM
v8volvo v8volvo is offline
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That's right I read about that closure too, forgot that. Crazy!

As for the mechanic's next steps, the biggest advice would be to just make sure he doesn't make the problem worse than it already is by making any unforced errors. Think through the potential consequences carefully on any diagnostic steps, such as that pressure test which was a risky move if the engine was started afterwards without removing glow plugs or injectors to clear cylinders first, assuming that was not done. Remember this is a diesel engine. The compression ratio is over 20:1 so you cannot tolerate ANY quantity of liquid in the combustion chamber or it will cause instant catastrophic damage as soon as the starter is engaged. The biggest risks to avoid are hydraulic lock (can occur if coolant from a failed headgasket enters cylinders) and contamination of the engine OIL with coolant. This is the reverse of what you have seen so far -- oil in the coolant -- but if it's going one direction it can often also go the other through the same interface point. Glycol in the coolant damages engine bearings, meaning the damage would spread to repairs to the bottom end of the engine also.

I would recommend sending an engine oil sample drained off the bottom of the sump after sitting overnight to a lab for analysis to have them check for presence of glycol in the oil. If there is any, DON'T run the engine with it in there, dye or not.

I am not clear on what the dye is intended to accomplish. Since the leak you are searching for is internal, the dye will obviously go everywhere the oil goes regardless of the source it's originating from. Maybe we are missing something on that? Or is he searching an external leak?

Your goal now is to limit the repairs to replacement of the headgasket or whatever failed -- not other things that suffered collateral harm! The more limited the repairs the faster you will be able to get your truck back on the road, particularly if you can avoid having to haul the entire engine out

As for the reason for the failure -- keep in mind you will want to devote some time to figuring out WHY this happened in the first place, rather than just reassembling after you find the point of failure and then assuming it won't happen again. If the root cause is still there, it will happen again, probably as soon as you attempt another trip where the engine has to work hard.

Remember no amount of new parts will guarantee a reliable engine if the engine is sabotaged during assembly.
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  #7  
Old 08-13-2021, 11:13 AM
ngoma ngoma is offline
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Very good, very methodical, very detailed explanation.

Yes so maybe we can find out more about what went into this HG R/R.

What was the surface preparation? Was it sufficient for the HG type (fiber or MLS)? Some experienced D24T-ers swear by a very light misting of Hylomar spray dusting on both sides of the HG.

Was the cylinder head checked for excessive warping or twist?

What type of fasteners? Original type triple-square screws, or studs? New or reused?

How tightened? In stages? What torque levels? Beam or clicker wrench? (as v8volvo mentioned above).

Re-torqued after 1,000 miles?



Also-- We should not categorically rule out the possibility of a defective oil cooler, even a new one. Although the symptoms do appear to be more consistent with HG failure, as stated above.
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Old 08-14-2021, 08:30 AM
v8volvo v8volvo is offline
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Quote:
Originally Posted by ngoma View Post

Also-- We should not categorically rule out the possibility of a defective oil cooler, even a new one. Although the symptoms do appear to be more consistent with HG failure, as stated above.
Good point and true. The oil in coolant could have come from there. Although oil cooler failure would not give a good explanation for the sudden overheating and cooling system overpressurization. Nonetheless, it could explain the other events too it if the cooler had in fact been failed for a while, coated the inside of the rad with oil and degraded hose condition resulting in the hose failure and that had caused the overheat episode.

The fact that the OP said the hose blew *after* the engine overheated suggests this theory would be off the mark, to my thinking at least, but then again, in the heat of the moment (no pun intended ) with many things happening at once plus trying to navigate traffic it can be hard to recall exactly afterwards what happened and how/when/what order. We all have been there. If the real sequence was that the hose blew first, or at least began to leak coolant out, then oil cooler failure could be the cause.

Oil cooler failure is not statistically common -- identical cooler used in millions upon millions of VW/Audi/etc vehicles worldwide from '70s to recent -- so we'd know if they were a trouble spot and probably a majority of those that do get replaced are wishful attempts where a head gasket problem is the real issue -- but infant mortality/DOA with new parts does happen, especially aftermarket. Headgasket failure OTOH is statistically common in engines where provoked by lack of due care paid to the preventive measures esp when combined with extreme operating conditions.

No reason to rule out the possibility though, pending further diagnostics steps, agree for sure. Sethsquatch can you remember when was the last time you had checked coolant level/appearance prior to this breakdown? Is there a possibility oil had been present in the coolant for some number of days/weeks beforehand?
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Old 08-14-2021, 11:06 AM
ngoma ngoma is offline
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Quote:
Originally Posted by v8volvo View Post
Oil cooler failure is not statistically common -- identical cooler used in millions upon millions of VW/Audi/etc vehicles worldwide from '70s to recent -- so we'd know if they were a trouble spot and probably a majority of those that do get replaced are wishful attempts where a head gasket problem is the real issue...
Interesting. I admit my thinking was thrown off by the minorly common practice of "going to remove that D@<!# failure-prone oil cooler before it causes a mess!"

Made me to think oil cooler failure was a thing.

But it appears to be an urban legend based on wishful fantasies (anything but admit to a HG problem).
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Old 08-15-2021, 08:26 AM
v8volvo v8volvo is offline
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Quote:
Originally Posted by ngoma View Post
But it appears to be an urban legend based on wishful fantasies (anything but admit to a HG problem).
I think that is correct. Cribbing from RockAuto below is the application list for the 068 117 021 type cooler. Note that the application years range from 1981 all the way to 2006 and include all of the highest volume bread-and-butter models VAG has ever sold, both gas and diesel... Furthermore this list is definitely incomplete (right off the bat I see it is missing 82-83 Vanagon and 95-97 Audi A6 and 04-06 Golf), and even more important, it only covers US market models. The rest of the world saw many models and engines that also used this cooler, probably into more recent years also. We can estimate that the number of vehicles produced using this exact oil cooler P/N is in the hundreds of millions easily. Then if accounting for other engines/models using closely similar design cooler with slight changes for fitment -- size or orientation of hose connections -- perhaps another hundred million plus.

None of these models are known for common oil cooler problems. They can fail and presumably do, sure. But not often. I used to see dozens of TDI cars come through a shop every week, plus other Volvos and VW diesels using this part, many reaching 250k, 300k, 400k plus mile ranges. Never saw a failed cooler -- not one single failure. If they had any kind of tendency to fail, the much more common applications like TDI would have enthusiast owners buzzing with the need to watch for it, and the whole world would be aware that 25+ years worth of incredibly diverse VAG products ranging from ancient beater Rabbits to shiny late model Audis to commercial and military trucks have an oil cooler that needs attention paid. A pandemic of oil cooler failures across a colossal global population. None of that is seen. Hence my skeptical opinion that it makes no sense this extreme low volume US Volvo D24T application would see hardly any failures at all, let a lone a high rate, and my guess that it is simple optimism or denial when people replace that cooler (or seek to eliminate it) after overheating their engine and finding oil in coolant afterwards....

Last of all, the use of one part in so many applications and with zero revisions across 3 decades is a pretty good vote of confidence from the OEM, who doesn't want to pay warranty repairs any more than we don't want to replace them all these years later, and uses failure rate data to make their decision.

All this simply to say to the OP (and whoever reading in the future with oil in coolant!), IMHO best not get your hopes up for an oil cooler failure, although certainly checking for it is always a smart idea in the interest of complete diagnosis. If you want to conclusively test the oil cooler for oil/coolant barrier leakage, you can easily disconnect the hoses and pressure test it in isolation from the rest of the engine. Either from the coolant side using a pressure tester, or by running the engine with coolant hoses disconnected at the cooler and see if it flows pressurized oil out the coolant hose connections. This process rather than dye in the oil would rule the oil cooler out.

AUDI 100 1992-1994
AUDI 4000 1982-1983
AUDI 80 1988-1990
AUDI 90 1988
AUDI A4 1997-2001
AUDI CABRIOLET 1994
VOLKSWAGEN BEETLE 1998-2006
VOLKSWAGEN CABRIO 1995-2002
VOLKSWAGEN CORRADO 1990-1992
VOLKSWAGEN EUROVAN 1993-2003
VOLKSWAGEN GOLF 1998-2003
VOLKSWAGEN JETTA 1981-2005
VOLKSWAGEN PASSAT 1993-1999
VOLKSWAGEN QUANTUM 1982-1985
VOLKSWAGEN RABBIT 1981-1984
VOLKSWAGEN RABBIT PICKUP 1981-1983
VOLKSWAGEN SCIROCCO 1984-1989
VOLVO 740 1985-1986
VOLVO 745 1985
VOLVO 760 1983-1985

https://www.fcpeuro.com/products/aud...17021b#fitment
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