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Testing for source of coolant in crankcase?

redshift96

redshift96

Diesel Knucklehead
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Location
Beautiful Soggy California
So I bought a very nice 85 Sub for a great price. It had a 6.5 crate motor (WITH Banks turbo system!) as well as a SR trans installed at a GM dealership in 1999. A couple of years ago the prev owner had an event of some sort (still trying to get more detail) which ended with the discovery of a significant amount of coolant in the crankcase. He thought it was a cracked head, so he bought and installed two new brand new heads, and fired it up only to pump more coolant into the crankcase. At that point, he gave up and sold it.

I'd planned to R&R the block, and I'm just about to pull it for that purpose. But then it occurred to me... I don't REALLY know where the leak is. For all I know, it could be a bad head gasket, or ... who knows what else?

So here's my q:

Is there any testing that is better conducted with the motor installed and in one piece? I keep thinking that it would be very smart to try to narrow down the location of the leak, rather than disassemble everything first and then take the block and heads to be pressure tested individually.

I really need to complete this quickly, as my loaner vehicle has to be returned very soon, and after that I'm going to be *walking* to the parts store!

I have another short block to swap in, but I'm reluctant to take the leap of faith that this will solve the problem without knowing for certain where the crack/leak/seepage/whatever is exactly.

So... any suggestions for the most efficient way of nailing down the location of coolant-to-oil leakage?

Huge thanks in advance for any help. This site and it's predecessors have been a treasure trove of great information over the past few years.

Pix and sig details to follow.
 
The only coolant could get in the tranny would be from the rad. You need a new one.
 
What NVW said brings up a question about your radiator. My 83 pickup has an engine oil cooler in one of the rad tanks. Does your rad have that same cooler in it? If so, has it been checked to eliminate it as the source of the rad fluid?

Don
 
An excellent point. Thanks much. I can probably leak test the in-rad oil cooler with air pressure and a gauge.

Any other typical places worth checking for water-to-oil leaks ?
 
NVW----It was your comment about the radiator that made me think about the oil cooler in my 83's radiator, otherwise I don't think my feeble memory would have brought it out.

The oil cooler is a long shot as oil most likely would also show up on the coolant, but long shots do occasionally happen, so it's worth either proving or eliminating the possibility.

Don

ps---not sure how easy it would be but if it was me I would totally disconnect the cooler, run the motor, and see what the outcome is.
 
Happy I could be of help in my infinite wisdom:rolleyes5:

That would be a lot better than doing head gaskets, good luck.
 
handcannon said:
NVW----It was your comment about the radiator [snip]
Click to expand...

Yes, thanks notwithstanding NVW!


handcannon said:
ps---not sure how easy it would be but if it was me I would totally disconnect the cooler, run the motor, and see what the outcome is.
Click to expand...

Well, I finally heard back from the PO. Says he found milky oil on the dipstick after running it for 15 minutes (incl a drive around the block) immediately following the head replacement. He pulled the pan, pressurized the cooling system, and saw water dripping down the #5 bore. Damn. Sounds like a new block is in my immediate future. Although... I guess it's still conceivable that it could be a faulty or incorrectly installed head gasket? Either way, time to pull it all out. Gah.
 
the water pump flows coolent threw the timing chain cover,, and if the timing chain cover gasket goes it will leak coolent in the oil... happend to me once...
 
Pull the thermostat housing off the engine full of coolant. Start the engine. A bad/cracked head gasket or head will show up as bubbles. Be carful of hydro locking it.

You are replacing the block so who cares on head gaskets water pump plate etc. You will be checking all of it anyway on teardown.
 
Annnnnnd, the verdict IS.... crack in one of the main webs, and abnormal wear on the corresponding crank journal. Forgot to ask which bearing it was, but I'll take pix of the failure when I go to pick it up.

So it's time for a new short block. Damn.

Anyone have a line on a used (running) or rebuildable 599 or late model 506? Any leads or help finding a suitable replacement for a reasonable price would be HUGELY appreciated.

I've found the "Canadian" blocks for $1500 online... quality and origin uncertain. Crate long blocks for ~ $3500 - $4500. At that price I'd just spend a little more for an Optimizer or P400, neither of which I can afford.

I may just overhaul a local red block 6.2 if I can't find a more suitable turbo block, but could get spendy pretty fast also...
 
These guys have tested and running 6.2's. $950.00 + shipping of ~$200 for me. Mine was spotless inside like it was rebuilt and left as a spare. 90 day warranty. I threw my 6.5 stuff on it and had to re-time the IP due to different 6.5 injectors.

If they have a 6.5 it would be $1500.

http://www.boyceequipment.com/

By the time you buy a master rebuild kit w/ pistons $1000 and machine the block $500.00... A military surplus makes sense.
 
Well, after coming *that* close to dropping $250 on an '82 red block motor (supposedly runs well), my local machine shop found me a 599 6.2 block for $500. Crank and rotating assy included.

That means I can go .030 over if I can find a set of pistons, or go .080 over and use std 6.5 slugs, which I have on hand.

So it appears it's time to start my own "599" budget build thread.

Will reuse the brand new Clearwater heads after having them checked over, and may replace the precups with GM parts.

Wow, so far that's two cranks, a 506 block, and a 141 block all headed to the scrap yard.

Thanks much for the suggestion, WarWagon. Considered Boyce but I really don't want to pull the motor again for a loooooong time. The 'unknown quantity' factor was weighing heavily on my mind. Might as well start fresh with the best block I can find.
 
And what is so special about the 82 red block engines?

If I had the time and more cash I would have started with a rebuilt 6.2 + ceramic pistons. But both were in short supply. So far 7K on the surplus engine.
 
> And what is so special about the 82 red block engines?

A very good question. I've been trying to dig out as much detail as possible about the evolution of the 6.2/6.5 block over time. Aside from the prevailing wisdom, I've found very little hard information on this. Sure would be great if some GM engineer could tell us exactly what mods were introduced in what years. Or maybe a wiki-style chronology of the castings could be assembled from all the collected experience on this board?

The ONLY advantage to the red block that I've seen cited has to do with it's metallurgy. Supposedly a higher nickel-content alloy was used. I have also seen a reference to the main webbing of the 660 block being increased during the 80's. But how the '82 red block compares dimensionally to any other block remains unknown to me.

And the bottom line (a least for me) remains: Is the stronger alloy of the red block sufficient reason to expect it to survive a higher HP turbo build? And does this make it any better choice than the 599 block?

My own answer ended up being: "Since I'm not sure, and since t DO know that the 599 was significantly thicker, I think I'll start there."

I think that if I were sticking with a NA motor, I might well have gone the same route as you, WW. But after tearing down two later NA 6.5's and finding some pretty severe problems after fairly low mileage, I'm biting the bullet and starting with a fresh bottom end. Sending the almost-brand-new Clearwater heads in for a once-over as well.

Can you tell I'm a little gun shy now?
 
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