vetzrul1

I have a huge oil leak and I can not find where it is coming from.

I've had oil leaking onto my converter and burning for some time now. Not really enough to do warrant a major issue but enough to be really annoying. After a quick inspection one evening from driving I noticed what appeared to be oil leaking from around the oil filter. I thought that over time the filter had loosened up some or the gasket my have gone bad so i planned for an oil change the next day since it needed it anyway.

So I changed the oil and filter and cleaned everything up. i noticed oil splattered around where the oil cooler mounting and just figured it was where interstate speeds had maybe blown the leaking oil around and didn't think anything else of it. I drove the car to work that afternoon and had no smoke when i pulled in and figured I was right and it was a simple fix. Drove home the next morning and by the time i got home I thought the car was on fire there was so much smoke. Looked under the car and there was oil 'leaking' from where it had been before around the filter. I looked a bit harder and noticed that it looked like the oil was steadily dripping down the oil cooler but I couldn't actually see where it was leaking from. I looked from the top and didn't see that much oil leaking from anywhere. I went through about a quart of oil in 20 miles.

The only thing I know of on the back of the engine that would leak that much oil is the pressure switch but I really didn't see any coming from that. I didnt see how an oil change would make it start leaking all of a sudden like that. I use Mobil 1 10-30 and have ever since replacing the engine. The engine has about 80k miles on it now. I've also noticed as of recently that I am starting to go through a lot of antifreeze but I don't have a noticeable leak anywhere at all which leads me to think the head gasket but I don't notice any smoke at start up or anything.

I'm completely puzzled on this but have to do something quick since that's my only vehicle right now and I'm thinking it's not a good idea to drive it with it leaking that much oil. Thanks for any info you guys may have.

92ragtop

Is there any chance that all or part of a rubber seal from a previous filter is stuck to the block? If that were the case, it could certianly result in a leak. (I always wipe the block mating surface to make sure that nothing compromises the oil filter seal.)

vetzrul1

No. Definitely nothing else on there. It was leaking before I changed the oil too. Just a LOT more after changing the oil. Is it possible for the oil cooler/adapter to leak anywhere?

aminnich

pressure sender by the filter housing is a good bet.

vetzrul1

I don't think it was coming from there. I am going to get it up on jacks and take a closer look though. It was dark and I was tired when I got home so I didn't look at everything as closely as I could.

MyFirst90coupe

Mine was leaking from the rear of the intake manifold and leaked all down the back of the block, I could see oil all over the filter adapter. It also looked like it was coming out of the head gaskets (I now know that is rather impossible). Anyway, I ended up changing the intake manifold gaskets and it seems to have stopped.

Good luck!

Jeff

383vett

Take the filter off and tighten the large nut holding the adapter to the block adapter, I think it's a 1" or 1 1/8" nut. A large crescent wrench will work.

vetzrul1

I've been able to get under the car and take a really close look at everything. It appears that oil is coming down the back of the block so looks like it may be the intake gaskets. So I'm going to start tearing that apart and dig a little deeper into it.

I also found some antifreeze leaking down towards the front of the engine which may be where I am losing coolant from. Could that possibly be from the front of the intake manifold as well or is it more likely the water pump or mounting gaskets?

leesvet

If you see oil running down the back of the block on the driver side to the filter,,...you;re oil pressure sender and low pressure switch fitting is loose, cracked or broken. Look below the driver side valve cover and toward the distributer. You will see the press sender and the 2 wire plug for the low press switch. The 2 senders are mounted in a T fitting in the block. Pull the wiper motor for more access.

PS
the sender thats over the filter is the oil temp sensor. its not in the pressure port, just free falling return oil for a temp taste.

Clean the area with dish soap & water or simple green...nothing harsh! that harness back there is fragile and has too many important circuits to risk a chemical degreaser bath.

John A. Marker

with leesvet. The sending unit and pressure unit screw together and are found on the back side of the block behind the distributor. They will leak massive amounts of oil in a short period of time. This is what they look like....

cgantner5150

That little 5.00 part (the 2 wire one) almost cost me my new 383. It didn't look oily when I looked at it but upon removal I could easily blow through it. Almost lost all my oil within a minute. Posted a thread about it a couple of weeks ago.

leesvet

OUCH !
Glad you caught it.
I know first hand how fast oil squirts out...

A few months ago when I was diagnosing a no-pressure condition I simply started the motor to see what kind of flow I really had... like a garden hose..

Imagine 50 lbs behind a good leak...oil everywhere.

cgantner5150

I can just imagine the fountain of oil shooting straight up - damn what a mess.

leesvet

yeah....it was about then I knew the problems were electrical....

vetzrul1

Thanks for the info so far. I started probing around and I do have oil all over the back of the block where the sending unit is so that may be what it us hopefully.

On the other hand I have also been looking for my antifreeze leak and found it leaking from the front of the intake manifold. So regardless of whether the oil leak is from the manifold or not, it's all gonna get changed.

I've gotten everything off except the fuel rail and manifold. At one time I had dexcool in the system thinking it was better and I was wrong. Is there a good way to clean the orange build up out while I have everything apart? I've run cleaners through the radiator before but it's never really gotten it all out.

leesvet

I've never seen orange build-up unless it was gummed from being added to a system that had not been 100% flushed and free of green. Original Dex had issues like that but its been modified to make it semi-compatable.
I have been running orange dex in my L98 for 5-10 yrs and never had an issue, but I also flush thru a permantly installed fitting & valve so there is zero remaining old coolant in the system.

Draining is inadequate, contamination remains unless its pushed out and when the thermostat blocks a major point of discharge or circulation there must be a "power-flush" with a water hose attached.

You might try the bottle brush, but other than that I do not know what else would be safe to get inside to remove and goop or residue. Perhaps returning to dexcool? I remember hearing some stories about gel and clogging and such but every one of them came from having some green left or someone adding dex to a system that was still full of green in the block where it had not been flushed out thourghly.

try to leave the rail w/inj on the manifold unless you are going to replace O-rings for the injectors.

vetzrul1

Thanks for the tip on the fuel rail. I was thinking I could leave it in the manifold but wasn't sure. I did decide to go on and pull the fuel rail off though because the manifold was kinda grimy looking so I'm going to do a real thorough cleaning while everything is apart.

As for as the orange stuff, it's not really buildup so much as it is more like a rust colored coating on anything the antifreeze goes through. I've done several complete flushes over the years more as preventative maintenance than anything. But anytime I flush the system and put clean antifreeze in it always discolors to a rusty dexcool color and I am positive I have gotten all the dexcool out long ago.

I did notice buildup in the two rear coolant ports on the head and intake though. It was kinda like mud. Best I can figure out is that stopleak I had put in during the winter gathered there since the gasket between the heads and manifold was completely blocking both rear coolant passages. Is that normal? I would think they should be open.

Anyhow, got everything torn down to the block and heads. I think I'm gonna change a few things around while I've got everything off both for function and aesthetics.

navy_vette

Stopleak cost my buddy a new radiator on his Honda (which was probably part of the problem in the first place). It was winter in South Dakota. If you leave it in after your warm the engine and then it gets cold (as in mid-west style 0 degress F cold), it turns into a rock. Be careful with that stuff.

One thing I would check in ref to the coolant is the water pump seal. If you have a small leak the pressure behind it would spray it everywhere and you won't be able to tell exactly where it came from.

leesvet

OMG !
thats the source of your next problem ! Glad you caught it.

I can tell you with 100% certainty that stop leak will SEAL off the rear coolant passages in the heads and cause a huge HOT_SPOT that will lead to a warped head or blown head gasket.

I used the stuff 2 yrs ago in an emergency to get home and pulled the left head off that weekend...passages completely closed. We had to chisle our way thru with picks and screw drivers before we could clean it out.

Thats probably whats discolloring the dexcool and messing with the motor,. those rear water passages are the slowest moving of any, so the gunk tends to collect more there than elsewhere. As the engine cools it hardens and you now have no water flow back there.

vetzrul1

Yea I'm glad I caught it too. But the weird thing though is that the gaskets themselves weren't even cut out for the two rear passages at all. One side was pretty clean other than the discoloration but the other side looks like it had a wad of mud crammed in it. I definitely won't be using stop leak any more after seeing that.