I've got an '86 GT here that's been waiting a couple years for me to do a bunch of "little" things to it before I sell it. It has a weird rumble emanating from somewhere in the engine bay that I haven't been able to pinpoint, even with a mechanics stethoscope. It seems loudest around the water pump, but I haven't been convinced that this is indeed the source of this odd sound.

Anyway, it also has a bad muffler that goes BLAT BLAT BLAT very loudly for several minutes after the engine has been started. I have another GT exhaust system here to swap in, so I dropped the old system down and had a look around while I was under there. With the exhaust system out of the way, things can be more easily seen.

This didn't look quite right...



So I had a closer look. Remember, I'm under the car looking up.



Should the front of the oil pan be that close to the inner hub of the harmonic balancer? I can't even slide a piece of paper through there!

What do you think - Could that be where the odd sound I've been hearing be coming from? Looks to me like it might be rubbing. If it is, can I simply pry back that part of the pan, or might that start a major oil leak there?

Suggestions?


And oh yeah, the other problem that needs to be dealt with... a broken lower exhaust manifold bolt on cylinder #2.

That is awfully close, I don't remember mine looking like that when I changed my pan, but can't figure out how it could possibly get misaligned. As for bending the oil pan back, I think you're right that you're just asking for an oil leak. There's very little torque on those bolts so you'll probably end up bending the part of the pan that seals against the block.

quote Originally posted by NetCam: ... but can't figure out how it could possibly get misaligned. As for bending the oil pan back, I think you're right that you're just asking for an oil leak. There's very little torque on those bolts so you'll probably end up bending the part of the pan that seals against the block.

Yeah, it's difficult to imagine the harmonic balancer could be in too far. But never having had an oil pan off, I don't know how far back to front the pan could've been installed... but I doubt it could've been moved very far.

That's actually the bottom of the timing cover that the oil pan is bolted to there. I think the timing cover itself is fine, it's just the lip of the oil pan that's awfully close to (and/or rubbing) the balancer hub.

This is exactly what happened to me. Yes, you need a balancer. Unfortunately you will probably have to get a Dorman that works, but has the timing mark in the wrong place. This is what TFS sells. I don't have the part number handy, but I'm pretty sure I posted it in another thread on the subject. You can try the Damper Doctor, but my experience is they don't have it in stock or rebuilding yours (if that's possible) will set you back, especially if you have to ship it back and forth to CA. I would get a puller, available many places for about twenty bucks, and borrow an installer from O'Reilly's or Zone. It's hard to get anyone to do it for you, let alone do it right, reasonable, and without screwing up other things. There are very expensive 'tunable' ATI balancers available from Summit Racing or Pit Stop for three bills, plus. I don't remember a rumble, but mine wasn't quite that bad. The other sound is of course your exhaust. I still have that too. Good luck! I think Advance has about the best price on the Dorman, about fifty bucks.

Fyi, I have one from an '85, for sale.

quote Originally posted by 85 SE VIN 9: This is exactly what happened to me. Yes, you need a balancer.

Hang on, hang on, hang on... not so fast.

I said it's the inner hub that appears to be rubbing the front of the oil pan, not the outer ring. I believe this harmonic balancer is just fine. The outer ring has not spun (or slid towards the block) on the inner hub as far as I can determine.

I should mention that I replaced the balancer on this GT six years ago...

quote Originally posted by Patrick on 10-02-2008: Finally got a harmonic balancer to replace the one which had “spun” on my GT. Here’s a picture of what I saw after I took the crank pulley off. Notice where the main timing mark and keyway are.

[This message has been edited by Patrick (edited 07-30-2014).]

what's shown.... balancer is not bad.

could be oil pan was replaced. Just look at timing cover.
looks like cover clears but pan is longer then cover.

If so, Cheap fix is cut off a bit extra pan metal.
Pull balancer then use Dremel w/ cut off wheels. Plug balancer hole w/ rags so no metal get into the hole.

Could be balancer and/or timing gear install w/ problems.

Bad main bearing from using clutch etc maybe can do this. Would easily show as axial errors. Push/pull on the crank (load front/back of engine) while helper measure how much crank moves. If you can easily see movement, is bad. (Very little movement is allowed.)

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[This message has been edited by theogre (edited 07-30-2014).]

quote Originally posted by theogre: Bad main bearing from using clutch etc maybe can do this. Would easily show as axial errors. Push/pull on the crank (load front/back of engine) while helper measure how much crank moves. If you can easily see movement, is bad. (Very little movement is allowed.)

This GT is an automatic, so I wouldn't think the main bearings have been subjected to the lateral stresses you suggested might've occurred with the use of a clutch. The motor actually seems pretty healthy, so I'd be quite surprised to discover that any bearings would be badly worn. But yes, I can see why looking at that picture might suggest that the crank has some "walk".

I was hoping not to have to pull the balancer, but in the long run it's probably the easiest way to access the front of the oil pan to grind off a bit of that protruding lip.

I'm still curious whether anyone else has noticed how close the oil pan is on their 2.8 to the harmonic balancer. I'm wondering what the width of the usual gap is.

[This message has been edited by Patrick (edited 07-30-2014).]

I would think the right tool could grind off a little pan wihtout removing the balancer.
It will take some digging in to fix that manifold bolt though too, is it leaking exhaust there?

[This message has been edited by 2.5 (edited 07-30-2014).]

quote Originally posted by 2.5: I would think the right tool could grind off a little pan wihtout removing the balancer.

Possibly a dremel I suppose.

quote Originally posted by 2.5: It will take some digging in to fix that manifold bolt though too, is it leaking exhaust there?

The exhaust is noisy when the engine first starts (typical leaking manifold sound), and then as the manifold heats up it quiets right down. It's always really bugged me though, and I suspect I'll have better luck selling the GT if I fix this. What the picture doesn't show is that there's also an A/C compressor in the way!

[This message has been edited by Patrick (edited 07-30-2014).]

quote Originally posted by Patrick: What the picture doesn't show is that there's also an A/C compressor in the way!

Yeah thats what I meant too, thats not the "fun" bolt

quote Originally posted by Patrick: I'm still curious whether anyone else has noticed how close the oil pan is on their 2.8 to the harmonic balancer. I'm wondering what the width of the usual gap is.

If I can remember to crawl under mine this evening, I'll check. (It's at home, and I'm at work now.)

quote Originally posted by TopNotch: If I can remember to crawl under mine this evening, I'll check. (It's at home, and I'm at work now.)

I appreciate the the offer, but keep in mind that the exhaust pipe does a pretty good job of blocking the view of the underside of this area. Those images I posted were taken with the entire exhaust system dropped and out of the way. I don't want you going through the trouble of crawling under your Fiero and then realizing you can't see this area very well.

Must be someone out there with a 2.8 on an engine stand, or has a good picture of one with the engine flipped over.

While I did share your skepticism when a CarX manager told me the balancer was 'walking' into the crankcase and should be replaced, he certainly appears to have been right. New balancer (and seal) stopped leak and opened gap. There is more of a gap on my SE also. Also, while I don't know of any examples, from what I read about how harmonic balancers work and why we have them, the damage from a faulty balancer can be 'catastrophic,' i.e. broken crank, ruined engine. I have some major complaints about how that shop replaced the balancer, etc., I can't argue with the diagnosis.

//www.fiero.nl/forum/Forum2/HTML/130453.html

[This message has been edited by 85 SE VIN 9 (edited 07-30-2014).]

quote Originally posted by 85 SE VIN 9: While I did share your skepticism when a CarX manager told me the balancer was 'walking' into the crankcase and should be replaced, he certainly appears to have been right.

I know what a failed harmonic balancer looks like. I replaced one on this very Fiero!

The balancer that's on this GT is fine. You can see in the images I posted that the outer ring and the inner hub are perfectly lined up.

The oil pan appears to be rubbing the inner hub. This inner hub does not move in relation to the crank when a balancer fails. It's the outer ring that starts to roam.

The only way the entire harmonic balancer could be moving towards the block is if the crank itself is moving towards the back of the engine (due to worn main bearings). If that was the case, replacing the balancer would solve nothing.

I pulled the harmonic balancer off. It's difficult to see, but the hardened sealer has definitely been rubbing on the backside of the harmonic balancer. And it looks like there's two or three very small areas where the metal lip of the oil pan has been "polished" by the balancer as well.



The harmonic balancer itself is fine.



So I'll just take a flat file and remove a tiny bit of the front oil pan lip. That should be enough to prevent any potential future rubbing, and hopefully that was the cause of the weird sound I was hearing but couldn't pinpoint.

Here's the gap on mine, after ten months with new balancer.

quote Originally posted by 85 SE VIN 9: Here's the gap on mine, after ten months with new balancer.

Looks pretty close. Thanks for crawling under there and taking a picture.

I filed the lip of the front of my oil pan, and I can now slide a .040" feeler gauge between the pan and the balancer.

I expect it to now be fine, but I won't know for sure until I finish dealing with the broken exhaust manifold bolt(s).

Yeah, on the early V6 the harmonic balancer comes REALLY close to the lip on the oil pan. It looks like the lip on your oil pan had some extra material sticking out, which can be trimmed. And judging by your last post, it seems you trimmed it. So you should be good to go, in that respect.

quote Originally posted by Blacktree: Yeah, on the early V6 the harmonic balancer comes REALLY close to the lip on the oil pan. It looks like the lip on your oil pan had some extra material sticking out, which can be trimmed. And judging by your last post, it seems you trimmed it. So you should be good to go, in that respect.

Just for comparison the 4.9L Cadiilac engine also comes very close to the front lip of the oil pan where the front cover meets. I measured about .040" clearance on mine which IMO is very close and maybe too close. The balancer ring aligns with the hub fine and it also sits flush with the end of the crankshaft. .
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
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[This message has been edited by Dennis LaGrua (edited 08-04-2014).]