Pinzgauer oil in coolant.

[Sethsquatch]

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!

[v8volvo]

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.

[Sethsquatch]

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!

Originally Posted by v8volvo

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.

[ngoma]

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.

Originally Posted by v8volvo

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?

[Sethsquatch]

Originally Posted by ngoma

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!

[v8volvo]

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.

[ngoma]

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.