87 Cadillac Seville ,4.1 with blown head gasket

Ed Locker · #1 (**permalink**) 07-02-04, 08:08 PM

Hi All

Just found out that the Head Gasket on my '87 Seville (4.1 Liter) has a blown Head gasket.All the anti-freeze is now in the oil.

I've been told that these motors can't really be repaired,it's best to replace the motor.

Head bolts don't want to come out of the Aluminum block without cracking the block itself?

Would anyone advise ?

Thanks,
Ed

BeelzeBob · #2 (**permalink**) 07-02-04, 08:42 PM

Sounds like you have been ill advised....

The engines are actually very easy to work on and very repairable.

The problem comes from inept mechanics applying the wrong techniques to try and work on them. Get the service manual and follow the correct procedures and the engines are very easy to repair.

I have never heard of the specific issue of the head bolts being hard to remove and cracking the block. Any bolt in aluminum builds a certain affinity for the aluminum after 18 years.....use an impact to zap them loose and they will come out fine. The shock load of an impact is the trick to removing them.

Most of the problems with those engines come from lack of cooling system maintenance. If the coolant is not replaced frequently (2-3 years/24-32K miles) the corrosion inhibitors in the coolant fail and the gaskets rot from the inside out.

The most frequent cause of the "coolant in the oil" is actually a failed intake gasket at the coolant crossover passage in the intake manifold. Much more likely source of a lot of coolant suddenly in the oil than a head gasket.

If the head gasket were to fail on the engine it wouldn't generall leak coolant into the oil... It might leak compresssion into the cooling system and overpressure it blowing the coolant out.... The head gasket can fail along the deck rail of the engine on the valley side and allow coolant into the oil...but that failure mechanism is a very slow seepage....not a sudden quantity of coolant into the oil...

Was the "head gasket" diagnosis something arrived at via pressure testing the cylinders or was it a conclusion jumped to upon noticing the coolant in the oil?? Drain the cooling system and pressurize the system with a hand pump on a cooling system pressure checker and listen for the sounds of leaking air to find the leak. Bet it is the intake gasket......

Be advised that the rocker arm support bar comes off as a complete assembly on those engines. Do NOT remove the individual rocker arm pivots from the bar or the bar will be stripped and the pivots broken. First mistake most mechanics make working on the 4.1 and then blame the engine for their ineptness.

Ed Locker · #3 (**permalink**) 07-02-04, 09:06 PM

Thank You very much for that clear reply.
The conclusion was jumped to....the dip stick was pulled and a very large quantity of a creamy color goo was on it. Also the radiator was bone dry and the ground under the car was dry,also.

I have babied this car,it was given to me by my Mom after my Dad died in 1995. I have had the collant changed every 2 years because I was told horror stories about the 4.1 if the collant wasn't changed. These rather large pellets are always added with the collant.
The Motor only has 77K on it and rarely sees 70 MPH.

Thanks again,
Ed

Ed Locker · #4 (**permalink**) 07-02-04, 09:18 PM

Duhhh.........It's a Deville,not a Seville.

BeelzeBob · #5 (**permalink**) 07-03-04, 01:10 AM

I would guess you have an intake problem then as stated above.

If you want to be sure then pressure test the cylinders with shop air into the spark plug ports (make an adapter from an old spark plug shell or use the fittings from a compression tester). Use 120 PSI for 5 minites or so in each cylinder and watch the (full) cooling system for bubbling at the rad cap. I suspect that the head gasket combution seals are fine.

If you are religiously using the coolant supplement pellets then likely they would have sealed any possible head gasket seepage at the deck surface on the inboard side. That is exactly the type of situation the supplement/sealer is designed and tested for.

I would pop the intake off and check the gaskets. If not the intake, then go to the front cover/water pump seals and gaskets...but I'm still betting on the intake.

BeelzeBob · #6 (**permalink**) 07-03-04, 01:19 AM

After you find the leak and replace the intake gaskets or whatever....

Change the oil and filter. Coolant immediately clogs oil filters and causes them to bypass...so don't even think of even starting the engine with the oil that is in there and filter that is on the engine now.

I would recommend going to a GM dealer and buying a quart of GM EOS (Engine Oil Supplement) .....when you pick up the gaskets.... Add the fresh oil and filter and substitute the quart of EOS for 1 quart of oil. Run the engine to assure no more leaks and that every thing is cool and replace the filter again. You want to make sure that any residual coolant that is flushed out of the engine after repair is trapped at the filter and removed immediately.

The EOS is important to the future life of the engine as it contains high quantities of the anti-wear substance ZDP. The ZDP (normally found in oil but in much lower concentrations) will help prevent any further wear at any incipient scuffing or scoring (like on cam lobes or at the distributor gear) caused by the coolant intrusion. The ZDP will prevent any further microwelding at the wear sites and allow the areas to burnish and "heal" rather than progress to a catostropic failure. That is exactly what the product was designed for...assembly and breakin lube and extra anti-wear protection in the event of a lubrication breakdown...like as in contaminated oil with coolant.

Do this.

BeelzeBob · #7 (**permalink**) 07-03-04, 02:17 AM

BTW....the oil that you want to be using in your engine is the Delo or Delvac or Rotella heavy duty SL rated oil. It is available in most discount stores in gallon jugs. That oil is NOT rated for GF3 or GF4 service in "gasoline engines" as the Delvac et. al. oils do not contain the friction modifiers that give the GF oils their fuel economy improvement. That is a good thing for your 4.1. Your engine has flat tappets and a cam gear driven oil pump that needs the extra anti-wear package in the HD oils that are actually designed for Class 8 diesel truck engines. It will work great in your 4.1 and provide better protection than normal engine oils on the shelf today that are rated GF3 or GF4.