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Discussion Starter #1
I have a 93 sedan deville with a 4.9L. I purchased this car for my wife to drive. It is nothing super fancy just a get around town car. Since I bought it and have started to do the usual maintenance I have noticed it has oil in the coolant. I am fairly mechanically inclined and am thinking this is a head gasket problem. But not being familiar with the cadillac engines I am wanting some more input. It is pumping a fair amount of oil into the coolant. Where should I start?
 

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Start by reading every post on here concerning 4.1/5/9 internal coolant leaks. You will soon figure how to filter the bunk from fact. Sounds like you are dealing with an intake gasket problem and not a head gasket leak. good news. Do not drive the car, pass go or collect $200.00 until it gets repaired.
 

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I do not think it is headgasket. Probably your oil cooler inside intake radiator tank leaks some oin into the radiator. I would drain the coolant and retighten the fittings on the the end tank to make sure the o-rings do not leak oil into coolant.
Probably there are other sources of oil leak into the coolant.
 

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Discussion Starter #5
Ok so I have one vote for intake and one for oil cooler.


I didn't know it had a factory oil cooler. I did stumble across the ps fluid cooler while changing the fuel filter.
 

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Intake and head gasket leaks will not cause oil in the coolant.

A leaking oil cooler in the radiator end tank will cause oil in the coolant. No question. That is what it is.

Follow the oil cooler lines from the oil filter adapter at the oil filter. They go to the end tank of the radiator. You can remove the radiator from the car, unbend the tangs that crimp the end tank in place and remove the end tank. That will allow you to remove the oil cooler in the end tank and replace it.

If the car is just driven locally and never used for towing or anything it is fine to disconnect or bypass the oil cooler if you want to for a beater. Just cut the oil cooler lines/hoses near the radiator fittings and hook then together to bypass the cooler. Use a piece of tubing and clamps. If you do this, use double clamps and safety wire the clamps together the keep the hoses from pushing apart when the oil pressure is high on cold starts.

It is perfectly fine to run without the cooler. The oils since the engine was engineered for 1992 have improved considerably and will easily handle the normal operating temperature of the 4.9 unless you are doing some heavy duty driving such as towing or continuous hill climbing in a hot ambient.

Use the 15W40 Delo/Delvac/Rotella oils in it and it will be fine without the cooler.

You should take care of this ASAP as likely coolant is getting into the oil but you don't see it. That will happen when the system is shut down and the hot (pressurized) radiator pushes coolant into the oil side of the cooler. This has the effect of depleting the oil and causing potentially severe engine wear.

I would bypass the cooler or replace it and change the oil immediately. Use the heavy duty oil mentioned and add a pint of GM EOS (engine oil supplement) available at any GM dealer to spike the oil with the ZDP antiwear additives to prevent any further scuffing or wear that may have started. Don't delay and don't bypass the oil change and EOS addition.
 

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I would first try to retighten the big metall nuts there the oil cooling lines enter the inlet radiator end tank (driver side). If it does not stop leaks more radical steps should be taken immediately. If you decide to remove the radiator end tank it makes sense to replace the both end tanks with new ones from gmpartsdirect.com. They are cheap end will come with all the necessary gaskets, which will cure your leaks most likely. The plastic end tanks are notorious for cracks. I replaced mine a year ago following chevelle's advice and am glad I have done it. He knows what he's talking about, believe me! LOL
 

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I'm not sure that tightening the oil cooler fittings will do anything for the leak described. The oil cooler fittings are like a bulk head connector thru the side of the plastic end tank. There is a nut retaining the cooler bulkhead fitting tight to the end tank. Overtightening that will probably crack the end tank and will do nothing for an oil cooler leaking internally. That nut does not seal oil at all. The tubing fittings on the oil cooler pipes could leak but they would not leak internally into the coolant. Any leak there would be externally and you would see it and it would drip on the ground. So, overtightening the tubing fitting will not help either.

You are not going to fix anything by overtightening the oil cooler fittings on the external connections to the radiator end tank.
 

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chevelle said:
I'm not sure that tightening the oil cooler fittings will do anything for the leak described. The oil cooler fittings are like a bulk head connector thru the side of the plastic end tank. There is a nut retaining the cooler bulkhead fitting tight to the end tank. Overtightening that will probably crack the end tank and will do nothing for an oil cooler leaking internally. That nut does not seal oil at all. The tubing fittings on the oil cooler pipes could leak but they would not leak internally into the coolant. Any leak there would be externally and you would see it and it would drip on the ground. So, overtightening the tubing fitting will not help either.

You are not going to fix anything by overtightening the oil cooler fittings on the external connections to the radiator end tank.
Right... tightening the nut on the end tank would rather prevent leaking coolant out of the end tank... Sorry for the confusion.
 

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Discussion Starter #10
I am gonna try bypassing the cooler tonight. If that stops the leak then I will get the new cooler and put it in.

Thanks for the help and I will keep you updated on what I find.
 

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Just be sure and tie the clamps together across the splice with safety wire so the joint cannot blow apart under high pressure one morning..... Other than that, if it solves the problem I wouldn't worry about the loss of the cooler.
 

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ok the verdict is in. It was the oil cooler in the radiator. I bypassed it and flushed the cooling system and now everything is fine except for a small amount of oil still in the radiator but it isn't circulating it through the rest of the system. So I need to find an oil cooler or a new radiator. I am thinking I might just do a new radiator due to the oil that I can't get to flush out of this one. So what do you think?
 

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watchamakalit said:
ok the verdict is in. It was the oil cooler in the radiator. I bypassed it and flushed the cooling system and now everything is fine except for a small amount of oil still in the radiator but it isn't circulating it through the rest of the system. So I need to find an oil cooler or a new radiator. I am thinking I might just do a new radiator due to the oil that I can't get to flush out of this one. So what do you think?
Perhaps a new aftermarket radiator WITH coolers makes sense. Did you change the oil? Good luck.
 

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Discussion Starter #14
I changed the oil. Didn't look like it needed it but figured better safe than sorry. Do I need to use the supplement tablets in the coolant? I don't know what they are but keep hearing about them on here.
 

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watchamakalit said:
I changed the oil. Didn't look like it needed it but figured better safe than sorry. Do I need to use the supplement tablets in the coolant? I don't know what they are but keep hearing about them on here.
Buy Bar's Leaks Golden powder tubes for $1.44 at Wal-Mart and put them (2-3 tubes) in the radiator neck not surge tank. Or you can mix it with coolant before refilling. GM supplement is made from the same stuff (ground ginger roots) by the same company
 

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why do I need to use it? If I don't have a leak why put stop leak in? Just trying to clarify. Not trying to upset anyone.
 

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watchamakalit said:
why do I need to use it? If I don't have a leak why put stop leak in? Just trying to clarify. Not trying to upset anyone.
It is a highly recommended preventive measure. Your engine came with tablets installed by the factory. Both the coolant and the supplement must be refreshed every two years. When you have leaks it maybe too late...
 

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Sorry I took so long to reply but thought you guys might want to know I bought a new radiator from radiatorexpress.com for $129 shipped. Put it in after flushing the whole system again and the problem is solved. No more oil in the coolant. Also replaced both radiator hoses while I had the radiator out.
 

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watchamakalit said:
Sorry I took so long to reply but thought you guys might want to know I bought a new radiator from radiatorexpress.com for $129 shipped. Put it in after flushing the whole system again and the problem is solved. No more oil in the coolant. Also replaced both radiator hoses while I had the radiator out.
Thanks for reporting back Did the new radiator come with nternal coolers? Did you add Bar's leaks to coolant?
 
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