Cooling system mess...help me out

[tinfoil_hat]

Those drain plugs are right in the middle of the block, directly above the oil pan. On the drivers side it just looks like a 9/16" hex bolt head almost flush with the block. On the other side it is your knock sensor. It takes an 18mm socket if I recall. When I pulled mine nothing came out. I had to roto-rooter around in there with a length of heavy guage wire. Then all kinds of crap came gushing out.

I have done coolant flushes several times and the only time I felt like I really got the system clean was when I used two jugs of the Prestone flush and I drove the vehicle for a whole week. After that it took 6-8 full refill/ warm up/ drain cycles before the water came out clean. You want to unplug the heater junction so you can flush out the heater core too. I tried some tricks like cutting the diaphram out of an old thermostat to speed up the process but maybe I was just wasting time.

So are you certain you are getting oil in the water when you flush and it's not Dexcool sludge?

 

[MLX10]

I am not sure I suppose. It looks like oil in water when I'm flushing with water. I don't know what extremely old coolent would look like. If they look similar it's a possibility.

 

[Brother Al]

I would NEVER delete the oil cooler, loop it as a temp fix, but thats it. If you do any towing or 4x4 duty, you definately want to have the oil cooler. The only thing you should delete is the crappy stock flex lines and replace them with stainless hard lines, just make sure you leave enough room for movement between the engine and radiator or it will fail. (See brake hard line flex loops at the master cylinder for solution).

If the radiator's oil cooler tank is the cause, Id suspect there'd be antifreeze entering the oil once the radiator pressurizes... That said, deleting the oil cooler doesnt really solve any issue, especially if the radiator IS the cause, because that just means the radiator has already failed internally... and it most certainly will get worse, (see external leak or AF leaking into the transmission cooler = $$$$).

#1.) Keep checking your oil and transmission fluid for signs of antifreeze/water contamination. Motor oil & ATF will turn to milky-colored goo with water &/or antifreeze mix, not brown/black.

#2.) Get ready to replace the heater core, radiator, & water pump.

#3.) Only use "Peak" "Green" or an equivalent IAT or HOAT AF . If you have Dex Cool (OAT type antifreeze)... Get rid of that nasty crap ASAP... its good, until its not and was never "stock" in any GM vehicle until the 1996 models came out (some claim '95, but thats because they get confused...New models are sold 1 year before the actual year, ie, '96 models were sold in 1995).

Dex-Cool was GM's hush-hush solution to problems with their "composite engine components"... (plastic intakes & other 90's junk parts). Dex-Cool was initially sold to everyone as "Lifetime Coolant", until it was discovered that the "proprietary chemicals" (aka GM's version of Stop Leak) added to GM's Dex-Cool started to break down between 60-75K and congeal onto every internal surface of the cooling system. It was designed to work in fully-sealed cooling systems, & in theory, when a leak formed, the chemicals would congeal when exposed to air... like blood. Reality is that it is always getting some exposure in the real world, so it does need to be changed out. My take is to avoid the stuff. Granted, GM would never admit this, but they had to have known and seen during durability tests, that all of those wonderfully craptastic plastic intake manifolds would distort, contract, and eventually crack after "X" many heating/cooling cycles. GM thought they could save/make millions off plastic vs the traditional alloy & iron, even if they had to warranty-repair 1/10 of the vehicles using "composite components"...and they did. The bonus claim to plastic was a weight reduction and thus more mileage under CAFE (Federal Law: Corporate Average Fuel Economy)

 

[tinfoil_hat]

You have your facts somewhat skewed. The only intake that comes into contact with coolant is is the lower and it is aluminum alloy, not plastic. The upper is plastic but its out of the coolant loop. If you are thinking of the LIM gaskets it is widely believed that the 2-eha or whatever the hell is in Dex will eat the original plastic framed gaskets and soften them. There are also some very knowledgeable people who call BS. The "stop leak" you mention is not part of Dex. It was a seperate product added to the coolant at the factory.

There were several reasons GM ditched old fashioned green and adopted Dex. In fact, every other automaker had either ditched the old style coolants already or would within a few years. Part of it was better compatibility with aluminum engine components. Then there were increasing gov't regulations on the phosphates in old fashioned coolants.

Old fashioned coolants also relied on silicates for immediate corrosion resistance but these are hard on water pumps and percipitate very quickly out of solution and flake off the internal surfaces creating deposits.

I'm not defending Dex and in fact I have switched over from Dex in my '96 to Zerex G-05. But if you know you have the newer style LIM gaskets and you are 100% certain your coolant system is airtight then there's no reason not to stick with Dex. Flush it every two years and keep your eye on the coolant level.

 

[BIG_KID]

You could delete the oil cooler with no ill effects on the engine. My 91 4x4 doesn't have an oil cooler, so does the oil run cooler on mine for some reason where GM decided it doesn't need one.
I removed the oil cooler on my GMC typhoon and its turbocharged for gods sake.....

 

[tinfoil_hat]

Many of these trucks shipped from the factory without an oil cooler.

 

[BIG_KID]

Many of these trucks shipped from the factory without an oil cooler.

Exactly

 

[MLX10]

The problem is still the fact that I don't know where the oil is coming from. I'm not sure how to diagnose it. This Friday I will be changing the radiator, hoses, and thermostat. I will attempt to drain out the block and heater core. After that then I will attempt to figure out where this oil is coming from!!!!

 

[Mountianjustice]

I havent tried this this on our trucks, but have seen it done on a toyota.

Take the dip stick out, get a balloon and a zip tie and fasten the balloon over the dip stick tube. Start the truck, if it fills up with air you have pressure in the engine, good posibly of a blown head gasket/crack.

Worth a shot.

Joe

Also an excellent way to test a pcv valve. It can be done with a sheet of writing paper over the oil fill hole with the cap off. If it flutters up and down the pcv is bad or you got serious blowby it should just ever so lightly suction to the oil fill hole. I once ran a volvo 850 for many many miles with a major rear main oil leak by removing the pcv valve and running straight hose in its place. With the engine running it created a slight vacuum in the crank case and the leak would stop.

 

[MouthForWar]

Previous owner deleted the oil cooler on my '92 and continued to tow extremely heavy loads (6,000 to 7,000 lbs), for commercial purposes, weekly....with no overheating or related issues. For what it's worth.

And yes, I know for sure. He's been my neighbor for years and I watched them use it to haul asinine loads. Lol.

Apparently they're a known weak/leak point, and he was chasing low oil pressure issues, so away he did with it. Lol.