3.4 DOHC leaking coolant.

[walterdude]

Here's the text of the fix... The new o-ring can be purchesed from the dealer,,,, just make sure it's the updated, BROWN one. Don't have a part number handy....... Included is a picture I took just before I put the engine in my car.......
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Distributor Oil Pump Drive O Ring Fix
All 1991 - 1997 3.4L Twin DOHC Engines will eventually develope this leak. The engine when manufactured came with a hole to mount a distributer. Well GM decided to just plug the oil with a dummy idler. It is located at the rear of the engine against the rear head. Simply put, on the back side, on the transmission side of the engine. Inside is an O-Ring that over time deteriorates and will leak or piss oil with any pressure that it is given. Sometimes it will piss oil onto the crossover pipe and cause a smoke to emerge from the louver or under the hood. There are many methods to fixing this problem. Some include pulling the rear head, others include cutting a notch in the head. Here's a suggestion that will take less time and cost less money/frustration in the end.

The Fix:
1. Disconnect the Negetive terminal from the battery.
2. Disconnect the Intake Air Temperature sensor connector and the Mass Air Flow sensor connector (if applicable).
3. Remove air box (or intake) including the tube running up to the plenum.
4. Remove the driver side cooling fan.
5. Remove the exhaust manifold cross-over pipes.
6. Clean the entire area with your favourite cleaner, carb/brake cleaner works wonders.
7. Remove the retaining clamp with a 13 mm wrench.
8. Pry up on the plug with a flat head screw driver, remove the old o-ring, clean all the oil out of the plug (the parts that you can see). Install a new o - ring (Can be purchased from a dealer or fel-pro.)
9. Slip the new o-ring onto the assembly. Add some RTV sealant.
10. Place the plug back into the block, using the proper finess.
11. Replace the retaining clamp securely tighting the bolt.
12. Reassemble in the opposite order, connecting the battery terminal last.

Done. It is a good idea to allow the sealant to have the proper amount of time before testing it. Failing to clean the areas and do a good job the first time will result in having to do it over.
************************************************** ******************
Hope this helps,,,,,
Tom

[nequamminor]

A friend and I did the intake gaskets, and we replaced the o-ring on the throttle body. Gaskets looked relatively new, and no signs of leakage. O-ring looked pretty good too. Got it all back together, and it leaks just as bad as before. Its a little more predictable though. It probably doesn't mean much, but if I drive nicely, and keep it below 2.5k rpms or so, it won't smoke. If I drive a little more aggresive though, smoke will billow out of the hood. Same spot as always, right by the exhaust manifold. Could it be the quick connect fitting on the lower manifold? Now that I know exactly where it is, that's where it seems like it could be coming from, however I don't know how pressure sensitive the fittings are. Thanks for all your help guys.

[93Oldsdroptop]

Here's the text of the fix... The new o-ring can be purchesed from the dealer,,,, just make sure it's the updated, BROWN one. Don't have a part number handy....... Included is a picture I took just before I put the engine in my car.......
************************************************** ******************
Distributor Oil Pump Drive O Ring Fix
All 1991 - 1997 3.4L Twin DOHC Engines will eventually develope this leak. The engine when manufactured came with a hole to mount a distributer. Well GM decided to just plug the oil with a dummy idler. It is located at the rear of the engine against the rear head. Simply put, on the back side, on the transmission side of the engine. Inside is an O-Ring that over time deteriorates and will leak or piss oil with any pressure that it is given. Sometimes it will piss oil onto the crossover pipe and cause a smoke to emerge from the louver or under the hood. There are many methods to fixing this problem. Some include pulling the rear head, others include cutting a notch in the head. Here's a suggestion that will take less time and cost less money/frustration in the end.

The Fix:
1. Disconnect the Negetive terminal from the battery.
2. Disconnect the Intake Air Temperature sensor connector and the Mass Air Flow sensor connector (if applicable).
3. Remove air box (or intake) including the tube running up to the plenum.
4. Remove the driver side cooling fan.
5. Remove the exhaust manifold cross-over pipes.
6. Clean the entire area with your favourite cleaner, carb/brake cleaner works wonders.
7. Remove the retaining clamp with a 13 mm wrench.
8. Pry up on the plug with a flat head screw driver, remove the old o-ring, clean all the oil out of the plug (the parts that you can see). Install a new o - ring (Can be purchased from a dealer or fel-pro.)
9. Slip the new o-ring onto the assembly. Add some RTV sealant.
10. Place the plug back into the block, using the proper finess.
11. Replace the retaining clamp securely tighting the bolt.
12. Reassemble in the opposite order, connecting the battery terminal last.

Done. It is a good idea to allow the sealant to have the proper amount of time before testing it. Failing to clean the areas and do a good job the first time will result in having to do it over.
************************************************** ******************
Hope this helps,,,,,
Tom

How did you get the plug out without removing the cylinder head?

[nequamminor]

lol No no, not the oil distributer plug, the o-ring in the throttle body. It comes with the intake gasket kit. That's the only o-ring I replaced.

[93Oldsdroptop]

lol No no, not the oil distributer plug, the o-ring in the throttle body. It comes with the intake gasket kit. That's the only o-ring I replaced.

I understand that. I was directing my question to the guy (walterdude) that wrote the writeup on changing the 'o' ring on the dummy shaft on the 3.4 LQ-1.

I mean, there's about 1/8" clearance between the top of the dummy shaft and the cylinder head on the 3.4, so I'm curious about how he did it.

Actually, it sounds like a write-up for how to do the one on the 3.1........

[walterdude]

No it IS for the DOHC,, AND,, I haven't done the job myself. There used to be a link to it on this site and I couldn't find it. I HAD copied and saved it, so that's what you see..... Someone elses writeup!!!
Anyway,,,, that plug WON'T come out without a head removal. It's WAY too long.. You CAN get it up JUST enough to get in there and clean up and slip the new O-Ring over it. I've read about people using a dremel tool to make a notch in the cap for a little more clearence.. Also heard of grinding a bit of the head where it hits as well,, just not too much... I don't believe the last 2 are absolutely necessary and I've heard of people getting in trouble grinding the head... It IS a tight fit, but many have done it over the years Ive had a DOHC. Thankfully I've never had a problem. I've got a new engine in there,,, maybe I WILL have to!!! When I took that pic I looked pretty close and it definately looks do-able!!
I'm going to be doing that job on my friends 92 GTP shortly, so I guess I'll find out!!!
Tom

[93Oldsdroptop]

No it IS for the DOHC,, AND,, I haven't done the job myself. There used to be a link to it on this site and I couldn't find it. I HAD copied and saved it, so that's what you see..... Someone elses writeup!!!
Anyway,,,, that plug WON'T come out without a head removal. It's WAY too long.. You CAN get it up JUST enough to get in there and clean up and slip the new O-Ring over it. I've read about people using a dremel tool to make a notch in the cap for a little more clearence.. Also heard of grinding a bit of the head where it hits as well,, just not too much... I don't believe the last 2 are absolutely necessary and I've heard of people getting in trouble grinding the head... It IS a tight fit, but many have done it over the years Ive had a DOHC. Thankfully I've never had a problem. I've got a new engine in there,,, maybe I WILL have to!!! When I took that pic I looked pretty close and it definately looks do-able!!
I'm going to be doing that job on my friends 92 GTP shortly, so I guess I'll find out!!!
Tom

I fixed one on a 92 and I had about 1/4" to play with after I notched the top of the dummy shaft, I just do not see how you will be able to get that sucker out enough to get the 'o' ring off without pulling the head. I ended up using a couple of old smallblock Chevy distributor gaskets that I had laying around covered with high-heat RTV silicone. Worked fine, never had an issue with it ever again.

Good luck, I'll be watching for your writeup.