1991 I/C 5.9L Head gasket failure?
 

A friend of mine calls me, his oil pressure was dropping like a rock as he shut the truck off before the gauge could bottom, tossed in in neutral and pulled it off the side of the road. No fluids on the road, rad cap had leaked and blew a nasty mess of antifreeze and oil all over the engine bay. I'd hoped maybe it used an engine cooler, but it doesnt look that way after looking around.

Obviously, I won't know for certain until I tear it down, but a failure this big should be visable in the gasket I'd think. I'll have the head surfaced and checked before reinstalling.

This isn't a heavily modded truck, 230k mile daily work truck, looking at doing the head gasket, rebuilding the turbo(found oil in it when tearing it down, a little too much end play as well), valve adjustment, and plan on turning the stock injection pump up a little to make it a little stronger pulling truck.

I'm looking for any advice on parts I can get. I see the victor reinz gasket kits cheap, but I dont want to do this again, I'll pay more for cummins or other brand parts if they are worth it, but I don't need to do studs or anything for this old stock truck I don't believe.

Mighty diesel sells a marine .020 cummins HG, and some allen head bolts that I've been lead to believe are a step above oem without costing a fortune.

Just looking for any advice on parts, as well as my analysis of what went wrong with this truck. I don't know of any other way for water/oil to mix like this outside of a cracked block or head I suppose.

Thanks!

Id deff cut the filter in half and look for bearing matterial that the oil reason it would drop far enough to cause a problem like your explaining, i believe they do have coolers on the pass side of the block but ifm them fail it causes over heating of water temp not complete loss of oil pressure as for oil and antifreeze mixed probably head gasket but before i went and spent money on parts id look for metal.. and parts buy them on ebay no need for studs unless you want lost of boost pressure use stock head bolts there already stretched and ready to go make sure you put oil on threads allows for a more proper torque hope this help

I would pull the oil cooler off the side of the block and have it checked for leaks. Its behind were the oil filter spins on.:rocking:

Yep, 2nd on the oil cooler vote. That is your most likely problem unless it's modded to where it's pushing high boost numbers.

I checked the oil cooler on the passenger side of the block because I thought that is what it had to be as well. What I found when I dropped the two oil lines off the bottom of it was clean TRANSMISSION FLUID!! I've not worked on one of these, so I assumed it was an engine oil cooler looking at it, but apparently someone has converted it over to being a secondary tranny cooler? Oil that came out of it either was looked clean as could be, and without a doubt red as could be.

For the record, as best I can tell this old girl is bone stock 229k miles on it.

You are talking about the round tube on the side of the block but thats not the oil cooler the oil cooler is the part that the oil filter screws on to that bolts to the block I have never taken one out but I think thats where its at.

Yeah, reading this inspired a little more research on my part. Not sure why I couldn't find the info the first time I was searching, but yes, it looks like it bolts into the block and isn't external at all like I thought it was. I jumped the gun and already have the head pulled so I guess I'll take it to the machine shop and have it resurfaced as needed, and have the valves checked/done if needed and new seals. It's got 230k on it so a little freshening won't hurt but it's definately a pile of money that didn't need to get spent. Lesson learned I guess......

Well, I don't have to feel bad for pulling the head for no reason. Took it to the machine shop, and it needed some work. Having all new valve seats installed, new springs(some were actually broken), knurling valve guides to bring them back to spec. Needless to say she should run better once it's back together, going to rebuild the old turbo too, too much end play imo. You could actually cause it to bind up if you wanted.....

I plan to leave everything stock with the injection pump and so on, I did some reading that made me nervous about piston temps getting to high on the 1st gen's but I do wonder if there is anything I should do while it's all down for any performance gains? I'm not looking for anything crazy it'd just be nice to give her back to the rightful ower running a little stronger than ever. Maybe a 3200rpm spring?

3200 spring and remove the max speed screw. That alone brings a lot more spunk out of the VE. Could turn the stock fuel pin. That'll allow for moderate fuel increase while not increasing temps too much since the full power screw at factory spec will be left in tact.


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Spring seems simple enough.

Max speed screw....will that be part of the injection pump/is it covered in stickies above?

I need to look into turning the stock pin, alot more. Sort of thought that was the same thing as turning the pump up, but I simply don't know enough about this pump.....time for some how-to reading. Feel free to chime in with any tips/tricks/instructions though :)

Thanks!