Currently chasing an oil leak on the passenger side of the engine, dripping down and collecting on the engine cradle, leaving a line shaped puddle of oil on the ground. It's pretty awful. Last week I drove 200 miles for a work trip and had to fill my oil back up an entire 4 quarts along the way, and had to stay below 2.5k RPMs to avoid leaving a smokescreen of oil in my wake.

It's been extremely difficult to pinpoint as airflow has managed to blow oil absolutely everywhere, all over the engine bay. I spent almost all day today cleaning the hell out of the engine to make things a bit easier.

I've scoured my maintenance manual and I've come across many forum posts from years ago of others with the same issue, but none of them mentioned a fix. I want to be absolutely sure where this leak is coming from lest I start wasting time and money replacing gaskets that aren't the issue. Please tell me one of you Fiero gurus have run into this before!


This is my first Fiero and I'm in love with it, I've given up on too many projects but I refuse to with this one. This car was barely running when I first bought it a few weeks ago and I've nursed it back to running excellently, it's just this leak keeping her off the road. Help a young fella out?

EDIT: I am absolutely sure it's not the valve cover gasket. It's one of the first things I replaced when I was adjusting the rocker arms.

[This message has been edited by Kestrel (edited 11-07-2022).]

quote Originally posted by Kestrel: Currently chasing an oil leak on the passenger side of the engine...

Are you referring to the end where the pulleys are?

quote Originally posted by Kestrel: Last week I drove 200 miles for a work trip and had to fill my oil back up an entire 4 quarts along the way, and had to stay below 2.5k RPMs to avoid leaving a smokescreen of oil in my wake.

With it leaking that badly... I think it would've been pretty obvious to see where the leak was coming from while the engine was running, especially if the area had been cleaned up/de-greased beforehand.

Hey, Kestrel. Congratulations on your first Fiero! We've had the massive oil leak you're experiencing on our '84 2.5. In our case, the bottom of the dipstick tube came out of the sleeve it slides into in either the block or the oil pan (I don't recall which) because the slotted ear at the top of the tube, where it is secured by (I think) one of the exhaust manifold bolts, has broken off and allowed it to wander around a little. I fabricated a way to secure the tube for now, until I get the chance to replace the tube. Biggest leak taken care of. Still have a leaking timing cover seal, but our other 2 Fieros keep me from making that a priority just now...

Exact cause unknown. Problems I see....
Is 87/88 engine....

1. The lifter cover is installed wrong and nuts and washers isn't OE.
"bolts" have a rubber part goes on them then cover then washer nuts.
Need cover gaskets Example: MAHLE PS39841 and Permatex High Tack sealer to "glue" the big gasket to the cover.
Might use same nuts but need smaller washers.

2. some intake man bolts go into oil drains and push rod holes on the head. Has no pressure and unlikely will leak.
Worse... If you delete the engine hanger for 2 bolts on #4 cyl you will "Crush" 1 push rod because I-manifold is made to have extra metal from that hanger.
If the hanger is Missing... the manifold is weak w/o it and gasket may fail leaking coolant to outside, internal to #4 cyl, or both.
Use Only FEL-PRO MS93688 I-manifold gasket and Install Dry without any sealer.

3. If Valve Cover is leaking...
Replace the cover using Dorman 264-905 cover w/ new style cap.
Use FEL-PRO VS50179T w/ new bolts etc costing way more then other gaskets.

4. O-rings for TBI is wrong type. Green Is for AC and may fail. Correct type is Viton in tan or black.
DORMAN 800013 has 2 of each size but cost.... other Viton "kits" often do not have right sizes. I have HF kit but but not sure if that has right sizes...
The Nuts on these joints only hold the parts in place. The o-rings do all sealing with no pressure from the nuts.

If the TBI has iffy seals, regulator, etc... buy a "Rebuild Kit" that has most seals gaskets and regulator "rubber."

5. 87 engine because see old type oil pressure sender plug... Get 88 sender and plug.
See my Cave, Oil Sensor
Why? when bad old style like to drain the oil pan and fast when engine runs even tho works electronically. That is often shows are plug full of oil but can be other ways to "leak" pressured oil when engine runs there.

6. Pull Oil Filter and look that flange and filter face. Bad seal or other problems can to same as 5.
Over or under tighten the filter is a problem too. Example: Many use a wrench to install and way over torque then wreck the filter face...

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

I'm going to call front main seal where timing cover was tightened down before the main pully was set.

I had a main seal leak on my v6 mainly from the car sitting for 3 years. Before doing a major to change the seal, I tried Blue Devil main seal sealer, and have not had a problem with it since. I was not losing 4 quarts of oil though...

Check the condition of the tensioner pulley bearings. Mine were shot, and allowed the pulley to tilt sideways. The back edge of the pulley carved a nice circular slot in the timing cover.
I replaced the tensioner assembly (with Rodney's), timing cover, crank seal and harmonic balancer/pulley.
Mine leaked so badly, I called it The Fiero Valdez.

[This message has been edited by Raydar (edited 11-13-2022).]

Timing and often oil pan was installed by only RTV by GM...
After many installs them same way but doing the job wrong.

Example: The Big gap between T-cover and O-pan most RTV available to the public takes Days at minimum to cure enough to run the engine.
That if they clean the surfaces because RTV hates oil and other crap on part to seal.