: 1996 FWB - Fluid change to head gasket or complete overhaul? help

06-30-13, 09:23 PM
I am a long time follower and have used these forums with success for multiple problems in the past*. But this is only my second post for help.

1996 Cadillac Fleetwood Brougham purchased May 2007 with ~50,000 with all new hoses and new fluids. It is still garage kept and now has almost 75,000 miles on it.
It has never overheated. Regular engine oil changes with Mobil 1 synthetic either 5w-30 or 10w-30. I usually only drive it on long trips so it has been sitting in the garage for the last 4 or 5 months.

Current codes P0171 & P0174 - lean on both banks. I assume vacuum leak.

I noticed some fluid on the ground and thought if I was going to get under it I might as well knock out all the fluids (especially since the coolant was a year overdue).
I ordered everything to change the engine oil and oil filter; flush the transmission and replace its filter and gasket; pcv valve and air filter; fuel filter;
coolant, enough distilled water to flush a few times first, and sealant tabs.

First I changed the air filter and then went to change the pcv valve.
When I pulled off home plate WOW it seems a rat or squirrel had nested under it on both sides on top of the injectors.
There was a ton of pinestraw, acorns, and yes, you guessed it...ample droppings :ill:

I spent the next couple of hours with a respirator, rubber gloves, shop vac, and dental pick trying my best to deturd.
I finally got it clean enough to pull out the pcv and there was a tear on the underside of the rubber connector (pic attached).

I looked up replacements and all I can find is an elbow with three connectors. The one I had looked like just a piece of vacuum line.
Is the correct connector the 3 sided elbow?

Then I flushed the transmission fluid in 3 quart segments through the top return line because it would only push 3-4 qt out at a time.
I was hoping it would push it all out so that most of the fluid was out of the pan when I would drop it to replace the filter and gasket.

Next I raised one side of the car to drain the engine oil. The underside is an absolute mess. I think it is the transmission pan gasket but am not certain because of all the gunk.

Engine oil drained. New gasket put on oil plug. New oil filter installed. The engine oil had a strong gas smell.

I lowered the car to put in new oil and when I took of the cap and looked in the cap it was rust colored (pic attached). Never seen it before.

When looking down the filler pipe inside right at the top it looks like coolant mixed with oil on the metal (pic attached).

I opened the coolant reservoir tank. Coolant is about half a quart low. It has a slight sheen on top and oxidation (pic attached).
Is it possible that both the coolant is entering the oil and the oil is entering the coolant?

I have not replaced the drained oil yet and have not dropped the transmission oil pan yet.

What is the best route to take in this situation?


*Past problems resolved with the help of this forum.
Replaced fuel pump bc of varnish eating through wires.
Sentinel lights now working by cutting trunk security wire on trunk lock.
No rear or marker lamps corrected bc of bad park lamp relay.
Idler arm replaced.

06-30-13, 10:25 PM
Drain oil and examine it next. Radiator pressure test or compression test would be a good move. I dont know if I've ever seen an LT1 blow a head gasket.

06-30-13, 10:42 PM
I drained the oil and replaced the oil filter and oil plug washer.
The engine oil had a strong odor of gas, but it was not milky like what is seen down the filler neck in the third pic.
I have not replaced the oil yet...not knowing if i will need to do a full tear down.

Is the oil and/or engine running necessary to complete the compression and radiator pressure test?
Also, is it necessary for the pcv valve elbow to be installed to complete these tests?

Thanks for the reply and advice.

07-01-13, 01:01 AM
Both test are done with the engine off. Radiator test is real easy, compression test is pretty easy. Both tools can be rented from the parts store. Youtube will give you the basic idea of how to do these test. PCV doesnt need to be hooked up for test. Youll want oil in the engine for the compression test.

07-01-13, 12:44 PM
If there wasn't a "milkshake" when you changed the oil, I wouldn't worry about it. Condensation causes that icky goo on the underside of the oil cap and filler tube when the car sits a lot. It doesn't look like oil and coolant are mixing.

The underside mess is probably oil coming from up top - I would suspect the back of the intake manifold. Unless you see drops of red fluid on the ground and accumulating on the pan bolts it's not the transmission pan gasket.

Your lean codes and gas smell in the oil are the result of that broken elbow. Get that fixed and you'll be in good shape again.

EDIT: By the way, I don't think that's a tear in the PCV elbow. That's chewed through by varmints.

07-01-13, 03:12 PM
We had exact codes as your great car , we had those replaced you mentioned and plus EGR Valve because even after all these been swapped , check engine light kept coming on
I hate rodents , they always cause damages and do more harm than good

07-01-13, 03:31 PM
I agree with Jimmy. Condensation will cause the "milkshake" up at the filler tube (worse of the car is cold when you're working on it). If the oil looks fine on the dipstick, you're good. A bad PCV system can cause the issues you are seeing.
If you have a bad radiator cap, you can loose some coolant over time due to vapours. If the coolant system pressure test looks good, that's what I'd replace (I'd probably just replace it as good preventative maintenance).

07-01-13, 04:51 PM
Thanks everyone for all the advice. I will get on it asap.

If the leak is coming from the intake manifold should I just try tightening it up first or go ahead with a new gasket?

In regards to the pcv elbow, the only style I can find looks like the pic attached. The FSM pic looks like the metal line plugs directly onto the PCV nipple. My original looked like just plain vacuum line.
Which is correct? If it is the 3 sided one attached here, does the extra side need to be plugged? or left as is?

07-01-13, 05:40 PM
I happen to have a '96 LT1 from a B/D body in my garage (doesn't everyone?). Here is what I have for a PCV hose. Is this not what you have?


07-01-13, 11:47 PM
Yes I do have that ventilation hose and set up,
but I am curious about the connection from the ventilation pipe to the pcv valve on the other side of the engine.
Sorry for any confusion.

07-02-13, 08:21 AM
Oops sorry about that. I took a picture of the wrong pipe. This is what's currently on my spare LT1. It looks like they replaced the stock elbow with what you pictured. There's just a cap on the extra nipple.


07-02-13, 08:38 AM
Yeah, it seems that when you buy PCV valves now they all have that extra nipple. I think it's so it will fit more cars. One nipple is bigger, one is smaller. And they usually come with a plug for the nipple that is not in use.

I just did the PCV valve in my wife's lincoln and it was the same way. Original only had 1 nipple, new one had 2 (one large, one small) and a plug for the smaller nipple.