# Oil in the water! Water in the oil: GM 366 engine



## pdqdl (Nov 15, 2013)

We were testing our recently rebuilt GM 366 Targetmaster engine in the chipper truck. All was going well; engine sounded good, running smooth, no problems. Oil pressure, water pressure ok. This engine has rebuilt heads, a used block with everything mic'ed, new pistons, new gaskets...I don't think we cut any corners except by using used parts.

After about 30 minutes of using the knuckleboom crane to re-attach the outrigger, it blew off a radiator hose, splattering oil & water mix all over the engine compartment. The oil was still clean.

I went diagnostic, restarted the machine. Huge globs of oil/water were continuing to rise up out of the radiator in a solid stream, even with a garden hose flushing the oil out as it came up. After shutting it down, the oil had been converted to the same oil & water sludge that was coming out of the radiator.

The engine still sounds fine. Running like a champ.

We took the heads off today, but I cannot find any signs of where the mixing was occurring. I looked REAL close at the head gaskets, but cannot find a thing.

I figure this is the only way that so much oil could be injected into the radiator: it would have to be connected to an oil passage that was under direct pressure from the oil pump. *Does anybody have a clue as to where/how oil could be injected into the water jacket under pressure?*


----------



## Pelorus (Nov 15, 2013)

Any antifreeze in the crankcase?


----------



## pdqdl (Nov 15, 2013)

Pelorus said:


> Any antifreeze in the crankcase?


 
When the radiator hose blew off, it was reported that the oil was clean. After I ran the engine for 10 minutes, watching the white oil&water sludge flow out the radiator, the crankcase oil was completely contaminated with water. 

Apparently, the water (which started out as 1/3rd antifreeze) has been churned into the oil so thoroughly that there is no straight oil to be found. There is no separation of the water from the oil, even hours later. It's almost as if some soap was added to make the water mix into the oil in a non-separating emulsion. The emulsion is rather thick, not unlike a nice hot gravy.

I am pretty sure that we would find lots of water at the bottom of the oil pan. Haven't got that done yet.


----------



## 2treeornot2tree (Nov 16, 2013)

Sounds like a blown head gasket

Sent from my SCH-I605 using Tapatalk


----------



## blades (Nov 16, 2013)

On my current fords there is a heat exchanger for the oil. When eng cold heats oil by passing coolant through one side oil other, when eng hot reverse cools oil. this does not look like a radiator type unit more like a can with the hoses from the radiator attached. Oil is pumped from internal source. If that Gm mill has something like this it and it failed it would explain your problem. One of mine recently developed a couple of pin hole leaks blew 1/2the oil out of the crankcase in 300 ft.. If it would have been and internal leak of the coolant the result would be exactly as you have described. I did not even know that this exisited on my engines. got an education. It was a fairly easy fix, sourcing the replacement part was a bit challenging with out doing the dealer thing.


----------



## pdqdl (Nov 16, 2013)

I wish that it were as easy as a head gasket or oil exchanger. There are no oil passages from the block into the head; that all seems to occur in the intake manifold gasket. There is no oil cooler, so that is out too.

I would be happy to blame the intake manifold gasket, except that I think all the oil comes up the push rods and drains back down the surface of the head into the block. Quite frankly, I am not really certain how the oil gets up to the rocker arms, I have not pulled the lifters to see if they can be pumping oil up the lifters into the rocker arm area.

Yep. I have had the Ford diesel engine oil exchangers leak water into the oil, and go the other way too. This truck doesn't have one, so that option is out.


----------



## Pelorus (Nov 16, 2013)

Cracked cylinder liner?


----------



## dawzie (Nov 16, 2013)

Pelorus said:


> Cracked cylinder liner?


 
Times two
You said it was a used block, any history on the block??


----------



## griffonks (Nov 16, 2013)

Thousands of GM cars with the 3.1 and 3.4(I think) V6 engines had oil & coolant leaks and transfers do to plastic intake manifold gaskets. I personally replaced two in an impala. The last time I used a felpro gasket that was more expensive than the "Fixed" GM gasket.


Sent from my HTC One V using Tapatalk


----------



## blades (Nov 16, 2013)

Ah yes, the plastic intake manifolds, Had to replace them on two Buicks my folks had both v6, both developed vacuum leaks but no fluid leaks.


----------



## pdqdl (Nov 16, 2013)

Nope. no real history on the block. It just bugs me to think that a block could crack on an engine that was running fine, not hot or anything.

No cylinder linings in this thing, either. Besides, a bad cylinder liner wouldn't inject oil into the radiator. I've done been down that water in the oil from cylinder liners. That's a different story, though.


----------



## pdqdl (Nov 16, 2013)

griffonks said:


> Thousands of GM cars with the 3.1 and 3.4(I think) V6 engines had oil & coolant leaks and transfers do to plastic intake manifold gaskets. I personally replaced two in an impala. The last time I used a felpro gasket that was more expensive than the "Fixed" GM gasket.



But did the bad gaskets put oil in the radiator? I had LOTS of oil coming into the radiator, but I had no exhaust gases. I've seen lots of head gasket leaks, I know what that looks like.


----------



## TRISTATEFORESTRYEQUIPMENT (Nov 17, 2013)

just my input, when ever we have anything related to a 366 we scrap that motor and opt for a 7.4 454 or a 8.1 496. all these motors use the same exact wire harness, same exact motor mounts, same exact everything basically. the 366 compared to a 454 is night and day for power and reliability 

joe

www.tristateforestryequipment.com


----------



## pro94lt (Nov 17, 2013)

Was the block checked go straightness where the head meets? Same with heads?


----------



## pro94lt (Nov 17, 2013)

Also does it have an oil cooler? Look for lines going into the radiator


----------



## pdqdl (Nov 17, 2013)

pro94lt said:


> Was the block checked go straightness where the head meets? Same with heads?


 
To be completely honest, I cannot remember. We have been back and forth to the machine shop a whole bunch of times. As best I can remember, this head & block combination came out of an intact engine that we bought. While it was claimed to be in running condition, we took it apart and put the micrometer on everything to make sure there were no concealed problems. It all seemed fine, so we put it back together with the best parts we had. It seems to me that there was some sort of complication on the crankshaft being different or wrong for our installation, so that got swapped.

I think that there is no way my problem is related to the head & block meeting squarely. 1: there were no compression leaks into the radiator or exhaust. 2: there are no oil passages between the head and the block, so the gasket between them cannot be the cause of any oil being injected into the radiator.

*pro94lt*: no oil cooler on the engine. That would have been the first place I looked.


----------



## pdqdl (Nov 17, 2013)

TRISTATEFORESTRYEQUIPMENT said:


> just my input, when ever we have anything related to a 366 we scrap that motor and opt for a 7.4 454 or a 8.1 496. all these motors use the same exact wire harness, same exact motor mounts, same exact everything basically. the 366 compared to a 454 is night and day for power and reliability
> 
> joe
> 
> www.tristateforestryequipment.com




Yeah, I considered that. I couldn't find any of those engines, either.


----------



## pdqdl (Nov 18, 2013)

I found the problem. The solution is not so easy.

First, I wish to thank everyone for their input. I am sure that if anyone reading this thread had ever seen this before, they would have recognized it instantly. _I know I will never forget this treachery. Engines hate me._

What I feared worst has come true: there is a crack in the block, allowing common passage of oil into water, and water into oil. There are several hairline fractures in the "valley" of the block. They are running all the way across the lifters from one side of the engine to the other. Tiny little spiderwebs, they are about the middle of the block (from front to back), and the crack can also be seen when you look down the inside of one of the water jacket ports that go into the head on the right side of the engine. The crack crosses over the camshaft to the other side of the engine, but there is no water jacket by the crack on the left side of the engine. Given that we can see the same thin crack crossing over a lifter and continuing on, I must presume that oil can go through the crack.

It's all academic at this point, but I sure would like to know what could cause such a crack. It does not seem consistent with any cracks I have seen before. Given that it is in the middle of the engine, I am inclined to think that it would have been caused by some major stress, caused perhaps by overheating by it's previous owner. I don't see how freezing could ever cause this problem, because it is centered in an area where there isn't any water.


----------



## Goose IBEW (Nov 18, 2013)

That sucks!! I have been down this road before and know first hand what its like trying to do your best and having it blow up in your face, quite literally. Sorry to hear about this circumstance.

I wound up having great success with Promar engines. Your 366 long block is $2100 from them. I highly recommend them as an option if you are continuing on this endeavour. I would call them and discuss the core, there may be an issue there. Here is a link. Good luck which ever way you go from here.

http://www.promarengine.com/enginedetails.asp?partno='CH366-01'


----------



## pdqdl (Nov 18, 2013)

I have found two intact engines nearby; each is less than $500. Both are for sale by owners that say the engine is good. 

We will pull the pans, do some inspecting, and buy one. I have all the good working innards to at least two engines now; all I need is a bore to match my pistons and a good block. If the bore is too small, that's ok too. I know how to fix that.


----------



## TRISTATEFORESTRYEQUIPMENT (Nov 20, 2013)

buy a 454 and be done with it !! use car-part.com to find a good engine

thanks joe

www.tristateforestryequipment.com


----------



## pdqdl (Nov 20, 2013)

Car-part.com doesn't recognize bigger trucks, and it apparently does not allow searches by engine size, either. Probably good for other parts.

I bought a good looking intact engine for $350.00 off craigslist. We pulled the pan, inspected everything we could see. This engine appears to never have been installed after it was rebuilt; sadly, I don't really know any more history than that. I am rather concerned about the health of an engine that was rebuilt but never installed. The skirts of the pistons looked fine, cylinders were good (what we could see), cam lobes were ok, the thrust bearing looked new, and the engine turned over nice and smooth.

So...we are going to see if it works. We must put our water pump on it, and we will trade out the ignition system and carb, since we know they are working.


----------



## pro94lt (Nov 20, 2013)

I would do a compression and leak down test before I installed and prime the oil pump before you start it...


----------



## pdqdl (Nov 20, 2013)

Yep. That is part of the plan, although I don't think leak down will work too good on a V8. I imagine that the oil pump will get lots of spin & pump time before we get that thing started.


----------



## treeclimber101 (Nov 25, 2013)

Sorry man I just saw this thread and I woulda told off the bat that you had a crack somewhere. , mine went like that 2 years ago , thought I had a head gasket did that no better , then shortly after that I water to my lower bearing and we all know how that ends , when I put the new engine in , I had too also change the radiator because of the sludge build up , 366 are finicky engines but the parts are plentiful , I made mine into a 427 nite and day basically same block little shorter stroke but all the 427 upper parts are bolt on easy .


----------



## pdqdl (Nov 25, 2013)

Yeah. I posted the question, but I kinda thought it had to be a cracked block. I was hoping that someone with more knowledge than myself would volunteer some info that would maybe shortcut the decision process or maybe have a solution.

We found an intact block, ready to install. It was supposedly rebuilt but never installed. Only $350, I couldn't pass it up. We pulled the pan, inspected from the bottom up...it all looked beautiful.

It's all installed, it sounds really good. We are cleaning up the mess it made; it gets a test drive today.


----------



## treeclimber101 (Nov 25, 2013)

No real way to find that .


----------



## pro94lt (Dec 6, 2013)

How's it running


----------



## pdqdl (Dec 7, 2013)

Pretty good, but it doesn't quite have the power I think it should, and it has very poor fast idle power. When operating the crane, it either has to be speeded up or saved from dying. For a $350.00 junk engine, it sure sounds good.

It's a carb problem; I haven't had time to fix it myself, so it isn't fixed yet.


----------

