Oil in Coolant

[Boa550]

I just bought this truck 89 srw 2 weeks ago, this past weekend I lowered the idle to match that of my 94 (750 rpm, pretty close) and I noticed oil in the overflow bootle. But no coolant in the oil. I have a low oil pressure light come on whenever I shift to Drive or Reverse. Did some research and figured it could be a leaking oil cooler or a headgasket issue. It has a constant piston slap. I don't know what mods were done, but this truck hauls 85 mph unloaded on the interstate, and it feels like I could go much faster.

My question is this how long can I go like this without hurting anything too much? I'm strapped for cash and probably won't be getting to fixing this utill maybe late July, in the meantime it's going to be my DD, my 85 K20 just gave up (rings, timing chain, distributor, front end, cracked frame, broken u-joints, etc.)

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1994 3500 5.9L Cummins 4x4 reg. cab DRW, 4 inch exhaust, fuel plate foward, and gwk.
1989 2500 5.9L Cummins 4x4 reg. cab SRW, Stock (I think)
2009 2500 HD 6.0L Vortec 4x2 GMC CrewCab SRW, STOCK

[Old 'n Rusty]

The pressure light is no worry. Dodge senders go bad all of the time. The oil in the coolant usually means that the oil cooler is starting to leak. This oil cooler is in the water jacket on the passenger side of the engine. It is a bit of a job to change and a reason why one should use quality anti-freeze and change it every few years. Eventually, if it is your oil cooler, you will fill your rad with oil very quickly. There are other things which can cause this. A bad head gasket CAN do it.

As you are cash strapped, I would put the pressure cap on the first notch... not fully tight, just in case some coolant could migrate into the oil. I would keep my rpm's down and watch the coolant and oil like a hawk. A little coarse ground pepper in the rad may help and can't hurt.

How much oil are we talking about here? A tablespoon? When the cooler lets go you can get a gallon of oil and fast. Have you drained the rad? This will tell you how serious the leak is. It could be full of oil. If it has only a trace you may be able to nurse it along.

By the way, non-IC'd cummins' get hot fast. Never turn up the fuel unless you get a pyrometer. One run can cook an engine. It is the large injectors combined with lack of intercooling which can cause exhaust and head temperatures up and over the fatal level. Your '94 and, of course, the IC'd first gens are relatively safe to push hard without guages, your 89 and my early '91 are not.

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91 (08-90) D250

5sp 2wd 497k VE 'adjusted', 3200 spring, Pyro, boost, 3.54 ,:thumbsup KN, 1\8" timing bump, 25mpg city 30mpg hiway 20mpg towing 6k 5'er

R60/7, Volvo 245 GL, f150 4x4 5 spd, Ram 318, MPG's are in Imp gal's

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Last edited by Old 'n Rusty : 11-04-2009 at 02:09 PM.

[Boa550]

The radiator was a little low (less than a gallon), topped it off with a 50/50 mix I had laying around. I don't have the truck with me now, I work monday to friday in albuquerque and drive 120 miles home on weekends. And I'm tempted to pull the pyro out of the 94 and mount it in the 89. The oil looks good and the level is ok. Popped the top on the half filled overflow bottle and all I could see is black. Does anyone know what the oil cooler is made of (aka. aluminum, copper, steel) I could braze a patch if I find a hole in the cooler this weekend. I've had a couple bucks saved for new tires ($1200) for the 94, but this 1st gen is way more fun to drive.

It sucks to think I spent 4 grand in my 85 K20 on a carb, cam, radio, speakers, tires, tcase, clutch, paint, and the whole thing doesn't even run anymore

I'm hoping its the oil cooler, I'll pick up some oil, AF, and take a look at the oil cooler. What are your thoughts on brazing a patch on the oil cooler? It may not last long, but I just need a band-aid till next year when I hope to tackle all the mods on my wishlist.

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1994 3500 5.9L Cummins 4x4 reg. cab DRW, 4 inch exhaust, fuel plate foward, and gwk.
1989 2500 5.9L Cummins 4x4 reg. cab SRW, Stock (I think)
2009 2500 HD 6.0L Vortec 4x2 GMC CrewCab SRW, STOCK

[DrewJ]

If you look at how its made, brazing it is pretty much out of the question. A new one is about 315.00 from cummins and another 50.00 in gaskets. There are some used ones on Ebay usually 25- 30 bucks. If you went that route i would go to a radiator shop and have it checked before i tore the truck down so you know the new used one is any good. Its not too bad to do yourself, not easy but not too awful. I did mine about 6 months ago. If you look through some old threads someone had excellant pictures of what it looks like.

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91 D350 DRW 5sp/ 4:10s 4x2

[Boa550]

I flushed the coolant this weekend and it looked ok. Took the overflow bottle off and it's half full of mud and a couple teaspoons of oil. But there isn't any oil in the radiator, what gives? I'll keep an eye on it but it seems like someone just poured some oil in the overflow bottle for some reason. I seemed to have dodged a $315 bullet.

Thanks for your posts and help.

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1994 3500 5.9L Cummins 4x4 reg. cab DRW, 4 inch exhaust, fuel plate foward, and gwk.
1989 2500 5.9L Cummins 4x4 reg. cab SRW, Stock (I think)
2009 2500 HD 6.0L Vortec 4x2 GMC CrewCab SRW, STOCK

[Old 'n Rusty]

A previous owner may have had a problem which was fixed but the tank was never cleaned.

Someone may have dumped in some contaminated anti-freeze, it may have had a minor head gasket glitch which sealed itself. The explanations are endless.

Take the tank off, clean it with TSP or solvent. Get it all nice and bright.... and look at it once in a while, just to make sure it is not getting more gunk in it.

I am amazed at the amount of crap that builds up in some vehicles tanks, rads, brake and clutch reservoirs etc.

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91 (08-90) D250

5sp 2wd 497k VE 'adjusted', 3200 spring, Pyro, boost, 3.54 ,:thumbsup KN, 1\8" timing bump, 25mpg city 30mpg hiway 20mpg towing 6k 5'er

R60/7, Volvo 245 GL, f150 4x4 5 spd, Ram 318, MPG's are in Imp gal's