DOHC front and rear seal leaking

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draven
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DOHC front and rear seal leaking

Post by draven »

Long time lurker, only posted a few times..

I purchased a DOHC fiero a couple of years ago and have been driving it off and on to shake down any bugs in the swap from the PO, who did a fairly good job overall.

Quick history:
The LQ1 is a 97 crate with approx 14K miles with a 97 ECU and a base Darth Fiero hptuner image thrown in ... When I took delivery of the car it was running PIG rich and I found out that the PO had installed L67 injectors without retuning the ECU. I've gotten a set of 96 injectors installed and it passed emissions with flying colors...

While doing my last oil change I realized I've got oil coming from around the harmonic balancer and from around the block to 282 mating area.. this is indicative of leaking front and rear seals on the block, however, is it normal for an LQ1 with so few miles to leak in these two areas?

I'm getting ready to swap in an 88 cradle so I'll have have relatively easy access to replace both seals, however....

After reading the PO's posts on OE I found that he did not set the timing correctly between the two heads and essentially set both sets of cams with their flats up at crank TDC, buttoned it up and then proceeded to rail on it... he then shredded two+ timing belts before he figured out the problem. Is it possible that these actions could have somehow damaged the crank seals or am I possibly staring at a larger problem and these seals are just the first indications of something larger?

Below is the aftermath, quoted from OE, of running the cam 180* out of phase, e.g. cam flats both up at TDC, as he figured out his cam timing mistake.

"Just a Update on mine if anyone wants to know. I took the engine out and found belt and everything still in tact. ????
That wasn't good.... I did find that the timming chain had snapped. The tentioner was all ground up and laying in the oil pan. Some of the parts did get sucked up into the oil pump and damaged the gears. But....Fortunatly the oil filter did it's job. I am in the process of replacing oil pump, filter, timming chain, tensioner and other minor stuff. I did find the trush plate between the intermediate shaft and block was goudged. Replaced that too. The drive gears on the intermediate shaft and dist. shaft were good. I'm not sure what happened first but either chain broke because oil pump jammed up on tentioner parts and snapped chain: or chain broke and distroyed tentioner and then jammed oil pump. Judgeing from the groove on the intermediate thrust plate the tentioner was broke a little while before the cahin gave way."

Thanks in advance....
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Shaun41178(2)
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Re: DOHC front and rear seal leaking

Post by Shaun41178(2) »

it could also be leaking at the oil pan at the front and at the back. If the PO took the oil pan off to replace all of these things, its possible he wasn't carefull when reinstalling the oil pan and now it is in fact the oil pan leaking, and not the main seals.

My bet is the oil pan is leaking.
FieroPhrek working on that ls4 swap for 18 years and counting now. 18 years!!!!! LOL

530 whp is greater than 312
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

Shaun41178(2) wrote:it could also be leaking at the oil pan at the front and at the back. If the PO took the oil pan off to replace all of these things, its possible he wasn't carefull when reinstalling the oil pan and now it is in fact the oil pan leaking, and not the main seals.

My bet is the oil pan is leaking.
Thanks and quite possible. I'll get some pics up in a couple of days, however, some oil around the harmonic balancer/pulley has been thrown around the frame and fender area and the oil at the rear of the block looks like its coming through the tran gasket above the oil pan.. both of these are still giving me concern.

I'll know more when I pull the tranny off as I plan on replacing the clutch anyway so I'll be taking a look..(the custom 6 puck and pressure plate is a bit too chatty for part time commuter driving..)
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Emc209i
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Re: DOHC front and rear seal leaking

Post by Emc209i »

tentioner
It's been a while since I've seen someone spell tensioner that way. It's Procarnut's old car and engine, isn't it?


There are four seals to look at front and back. Two on the front, a "main" seal for both the crank and dummy cam, both mounted in the front cover. Two at the back, one is the large rear main seal, and the other is the cap for the dummy cam, which was mentioned to have been "gouged" before. The dummy distributor has an o ring on it, and leaks in the same manner as the normal dizzy's do on the 60*. In fact, that O-ring is "the" oil leak culprit reported a great deal of the time. The rear head has to come off to replace the o-ring. I would check the valley to be sure oil's not coming from there and seeping down into and out of the transmission case. Shaun's point is also valid, the pan seals the lower portion of the front cover in a peculiar way. An easy seal to botch.

Whatever the culprit, be absolutely sure you get everything absolutely perfect before you put the engine back in. You probably know who I am. Working on the DOHC in the car is a losing proposition. If something needs to be replaced, do it now. I can only hope GM fired the engineers who built that engine, tucking the dizzy shaft underneath the head.
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

Yes this is procarnut's engine and car. He did a great job on the swap and car, just a few rough ends here and there... but then again he wasn't done with the car either..
Emc209i wrote: There are four seals to look at front and back. Two on the front, a "main" seal for both the crank and dummy cam, both mounted in the front cover. Two at the back, one is the large rear main seal, and the other is the cap for the dummy cam, which was mentioned to have been "gouged" before.
Many thanks and excellent areas to look into regarding the dummy cam seals...didn't think of that... L67 on OE, correct? Excellent documentation on the F23, I look forward to using the knowledge you've garnered and posted thus far. With so little miles on the LQ1 I wouldn't expect the o ring to go so early, but we'll see... Expecting the worst, I've obtained the appropriate shop manual, the GM CPT with VHS tape, and the majority of the kent moore tool kit. Like I said, we'll see....
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Emc209i
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Re: DOHC front and rear seal leaking

Post by Emc209i »

draven wrote:L67 on OE, correct?
Yes, and thank you. But more importantly, Emc209i on both forums, the guy who lost thousands of dollars in a DOHC. That engine isn't the most beginner friendly, and it's nearly impossible to service while it's in the car. Be sure you've worked out all of the kinks before you put it back in. I'm actually surprised that engine is running as well as it is considering the abuse it's been through; broken chain, tensioners, belts, busted cam cover, etc.
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Aaron
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Re: DOHC front and rear seal leaking

Post by Aaron »

Emc209i wrote:
draven wrote:L67 on OE, correct?
That engine isn't the most beginner friendly, and it's nearly impossible to service while it's in the car.
I'm wondering if its even worth arguing all over again. By the way, mine is still running strong.

So, what is impossible to service that you'd likely need to service? I'll give you the distributor cap, however that being said I've never had one that leaked. I'll also give you the timing belt, but I don't think you'll find a DOHC engine that you can time in a Fiero.

Those out of the way, it's not that bad. Spark plugs are a hell of a lot easier than the stock 2.8l, and done fairly easily. Oil changes aren't any more difficult than any other car. The gaskets that you'd likely need to replace are all pretty easy. The alternator is a 10 minute job, and that's if your drunk. And you can easily access every sensor the engine has. With exception to the first two listed above, everything else is fairly simple in my opinion. And it's certainly a lot better in a Fiero than it was in a Lumina. Leave it to GM to accomplish that...
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Gooch wrote:Way to go douche. You are like a one-man, fiero-destroying machine.
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Series8217
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Re: DOHC front and rear seal leaking

Post by Series8217 »

The LQ1 DOHC V6 is great if you can take it apart, do all the right stuff inside (see below), and put them back together correctly. They'll run for a long time without need for any maintenance that requires pulling the motor. It's possible to do the timing belt with the motor still in the car; I've done it. If you hate to do it in the car... clutches may not last long, so you can do the timing belt when you change the clutch.

Things you need to do while the motor is out and apart:
1) New gaskets. Replace every one that you can. A full gasket kit for this motor is not expensive. You can even use a 3.1 kit for most of the gaskets.
2) Replace the intermediate shaft bearings, or at least the front one. It WILL fail. (Serious issue)
2) Seal the oil pump drive gear cap. This is the "distributor" plug people talk about. You need to put a new Viton o-ring on it, and then reinstall it with a SBC V8 distributor gasket with silicone sealant on both sides. It will never leak again. (Serious issue)
3) Port the drainback holes and remove internal flashing in the block. (Moderate issue; do this if you can.)
4) Tack weld the oil pump pickup tube to the oil pump. (Serious issue)
5) New timing belt, tensioner, and idlers. (Serious issue)
6) Sleeve the harmonic balancer if it has any visible scoring on the oil seal surface. (Minor issue)
7) Install King Bearings main bearings. these provide better rod oiling by means of extended oil pickup grooves. (Moderate issue)

The DOHCs don't have too many serious issues in a Fiero, but they have enough minor to moderate issues that they are extremely frustrating unless you do all of the above.
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Aaron
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Re: DOHC front and rear seal leaking

Post by Aaron »

While Steven is right on all of those, having a crate motor gives you some flexibility when if/when you want to do all of these. Of the four LQ1 crate motors I have, 3 of them have run trouble-free since they were installed. One is at 84k, one 15k-ish (And turbocharged), the other last I heard was just over 20k. The fourth hasn't been run yet.

For my crate motor on my turbo car, I was pulling the heads so I re-did the distributor plug just in case.
88GT 3.4 DOHC Turbo
Gooch wrote:Way to go douche. You are like a one-man, fiero-destroying machine.
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

I agree, having a crate motor does give additional flexibility.. I've even shopped around for a crate lq1 and have found several decent deals ~$400-500, but none are the 96-97 flavor. If anyone knows of one... please chime in or pm me...

The 97 monte ecu shouldn't have a problem with a 94-95 crate would it? its got both the 7x cam sensor and 24x crank sensor... but only has one knock sensor boss as opposed to 2 on the 96+. I'd like to keep the 96+ to keep from having to perform any additional exhaust fabbing to the current headers..
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

On another note, my lq1 investigation has been put on hold as my mothers 96 4.6 DOHC Lincoln has developed a vac leak, or lean cylinder bank, that I cannot track down.. I've put it against a smoke machine, fabbed a pressurized fuel injection cleaning kit using napa cleaner, sprayed every area I can think of with carb cleaner with no idle or fuel trim changes on my OBDII software..

I've torn off UIM and the variable length runner valve manifolds and reassembling with new vac lines and gaskets as I had nothing left to check... I may pipe in here to get some of you fellas advice...
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

Soaking carbonized variable intake runners and UIM from the lincoln in diesel, sure is a lot cheaper than chem-dip... around 1/4" of carbon buildup in the manifolds and TB....wow

Many of you might find this funny, I was watching the DOHC CPT VHS tape and while cover the engines technological advancements the narrator stated that the oil pump shaft drive and o-ring configuration for the TDC was an "Engineering Innovation" :shock:
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Emc209i
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Re: DOHC front and rear seal leaking

Post by Emc209i »

Corporate GM has been hyping up their crap to sales reps and technicians for years. Watch any of the dealership tapes that the sales associates are required to watch before walking out on the lot to close deals. "Although our car is underpowered, unreliable, plastic, and unrefined in comparison to our competition (fade in shot of competitor's car), it is important that you inform the potential buyer that our product is $2000 cheaper, and that's a REAL bargin." My favorite is one of the older videos, when they compare a Lexus SC300 to a Bonneville in the mid 90's. Cue camera pan of leather wrapped, wood accented, tech'd to the teeth interior. Cue plastic Bonneville interior, zoom in on SSEI sticker. The only selling point they had was that the supercharged Buick V6 had 5 more hp than base model 2JZ, and so they framed the Bonneville as a racing man's car, and the Lexus as an old mans car. Of course they failed to mention that the SC series was available with a 6 bolt mains, indestructible, racing pedigree DOHC V8 that kicked the living shit out of the old Buick engine. Conveniently comparing the base model competitor to their own top of the line model. Sales reps walk outside and sell Bonne's telling people that it's a race car. Sure, they're in the business of selling cars, but they use hyper-inflated information to sell their cars instead of real quality, and that quite frankly makes me furious.

The oil pump drive (dummy distributor) is quite literally a distributor with the top lopped off. I could build one with a 40 year old SBC distributor, a hacksaw, and a tube of JB weld. Yes, engineering innovation at its very finest. Where can I sign up to purchase a 2013 Cheby?! Pfft.
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draven
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Re: DOHC front and rear seal leaking

Post by draven »

continued in tech section to get more visiblity..
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