'93 3.8 has coolant in cylinder-help!
 

Hey All,
Vehicle is '93 Buick Park Ave w/ the series I (vin L) 3.8. She had been consuming a little coolant. Not being able to locate the leak, I thought the upper intake manifold was the problem. After removal and inspection it appeared fine. Put her back together. Then no start. Sounded like it was locked, so I pulled all the plugs - #1 literally had coolant drain out - ugh. I spun the motor and blew out fluids. So I apparently have a bad LIM gasket? Should I also change head gaskets? Car ran great before my "repair" (wife wants me dead). I previously had no heat buildup, no telltale white smoke from exhaust. Just an annoying coolant leak. If I can confirm its only the LIM gasket that would be great, but if I need to swap head gaskets I guess this would be the time to do it. You guys are highly recommended from a merciful fella on the Buick automotive forum and I would truly appreciate any help!
Thanks!
Scott

It's almost certainly just the lower intake manifold gaskets. The problem with the upper intake manifold failure is with the newer L36 (VIN K) engine, installed in GM cars starting in 1995. Head gasket failure in these engines in not unheard of, but it is extremely rare. I am not sure if the newer aluminum frame gaskets will work on your '93. I am guessing they will not and you will be changing out the old plastic LIM gaskets for new plastic gaskets. Someone else will be able to verify this for us. One thing to check. If somewhere along the line someone installed orange Dex-cool coolant in your engine, you will want to flush it out and replace it with the new "mixes with any type" coolant.

BTW, you can tell the wife you are doing the right thing in finding and repairing the internal coolant leak. The LIM gaskets can fail as yours apparently did, leaking into a cylinder, and often fail by contaminating the crankcase with coolant. When coolant gets into your oil, it attacks and destroys your bearings, effectively ruining the engine. To make sure you don't add to the damage, the safest course is to first drain the coolant. Then change the oil and filter. Then change out the LIM gaskets. When you get it running again, run the new oil for just a little while, then change the oil and filter again to flush any coolant that might have found its way into your oiling system.

BIll, Thanks - good info. Yes, had I been more thorough in my research I would have realized the the EGR stovepipe issue did not affect the UIM in the '93 3.8. No orange coolant, just the regular stuff. I've read up a bit on the alum framed LIM gaskets, I'll research the availability of these better LIM gaskets for the '93. I'm not real knowledgable on this motor...obviously! Any tips for swapping LIM gaskets. I assume the UIM and fuel rail needs to be removed (been there) OR can the UIM/fuel rail just remain and the LIM be lifted off?
Thanks again.

I suspect that you will need to go in the same way you did before, but I am not that familiar with the L27. If the L27 uses the same plastic frame, silicone bead gasket between the LIM and UIM, I do know that these can be re-used if they have not been in service very long. So, at least that might save you $30. I'll go get you some L27 help. I checked my FSM for the '92 L27. If the same in '93, the lower can be pulled with the upper. Here is the procedure from the '92 FSM:

Remove or disconnect:

1. fuel injector sight shield and air intake duct
2. spark plug wires on right side of engine and set aside
3. fuel rail
4. exhaust crossover heat shield
5. cable bracket to cylinder head mounting bolt
6. power steering pump support bracket
7. loosen generator and move to obtain clearance
8. generator bracket
9. heater pipes
10. bypass hose
11. intake manifold bolts and manifold

For installation, use threadlocker on IM bolts and torque in sequence to 88-in-lb.

There are no hidden bolts on the L27 lower intake like on the L36, so yes, the LIM and UIM can be pulled together. Aluminum framed LIM gaskets are not available for the Series 1 motors, but aren't needed. S1 LIM gaskets look good enough to eat off for many miles, and don't have DEX screwing them up (or shouldn't).

The procedure above looks good. Consider taking the TB off and cleaning it after you get the manifolds off the car. Be warned that the TB is alot easier to remove from an L27 after the manifolds come out than on the car. The L27 is a finicky little bitch when it comes to the TB, and you may lose skin. :lol:

I've also run into an L27 that had the threaded anchors on the UIM inlet for the TB spin in place. If you can, back this up with a wrench on the back side of the inlet flange when you break the TB nuts/studs loose.

Torque specs are in Techinfo.

ONE MORE THING. Almost overlooked this.

On the accessory drive end of the LIM is a threaded barb fitting for the coolant bypass hose. If yours is original, it's plastic. Go to the dealer and get a new one. They redesigned a few years ago to steel. Your plastic one has a limited lifetime and can dump coolant VERY quickly when (not if) it gives up. New part is cheap. Under ten bucks IIRC.

For the newer cars, this part would be similar in function to the Plastic Elbow on the S2. But this is a straight fitting threaded into the end of the LIM on the Series 1 cars.

Thanks guys. The procedure for pulling the LIM was spot on. Will, you were right about that bypass fitting, it was cracked and broke off the moment I tugged on the hose. Getting the remainder of it out of the manifold required some creative chiseling. I replaced w/ new metal fitting.My gaskets and seals appeared OK, but I replaced with new. The throttle body is a pain to get reinstalled, but I've just about got her all back together. Hopefully she'll fire up and go another 100K.
Great advice guys. I sure appreciate your help. Thanks a million.

If you haven't done so, change the oil ASAP ;)

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Dropped the oil, it appeared OK. I could see some coolant, but did not have visible separation of oil and water (no milky froth). No metal shavings appeared when I ran a magnet thru it...I was concerned since the engine hydrolocked when it was idling for about 10 secs, engine was not under any real load, just idle, so that was a concern. After I put it all back together, it started on third try; idled rough, blew a lot of white smoke for 'bout 30 secs...idle improved. Shut down and re-started and let run for about 5 mins. Temp and oil pressure were good, white smoke lessened, idle steady. I've got a leak aound the thermostat housing to address, but other wise looks OK. I'm gonna do more through check for leaks, hopefully the thermo housing is only one.

Not wanting to appear too anal about this part, but we all believe that you should still do another oil change to ensure all that water is out of the oil. This comes from long experience on the club and is worth the $20 or so for oil and a filter to ensure long engine life. ;)

:stupid: re the oil change.


I would also do a compression check on the engine. If you hydrolocked while the engine was running, even just idling, there is a chance that you bent a connecting rod. The fact that the engine runs at all implies that if a rod is bent, it is not too badly bent. But the compression check should reveal a bent rod as a cylinder with significantly lower pressure. Because lots of other things can cause low compression, I would not attribute a low reading to a bent rod unless the difference was pretty large, maybe 40-50 pounds lower than the rest. If you find a low cylinder, you could then do a cylinder leakdown test to determine if the leakage past the valves or rings was greater in that cylinder than the others. If the leakdown in the low cylinder is comparable to the other cylinders, a bent rod would be indicated. I would be concerned that a bent rod would pretty quickly spin its rod bearing, and damage the crankshaft journal.

I was planning on running the fresh cheapie oil I just put in for maybe 50 miles and then replace with the good stuff. Understood on the compression check. I've not done a compression check before ever, on any motor, and I know I must do one to get an accurate idea of whats happening in there. But is there a quick means or a gut feel for any of the issues noted? Motor starts right up, seems to have healthy idle w/ no suspicious noises. I've not done other than just idle and move from garage to driveway at this point. The hydrolock occured a week ago as I started engine, it idled rough for about 15 secs. then sputtered and stalled - after this misadventure, I drained coolant from #1, R&R all other plugs, pulled LIM - R&R gaskets and seals, R&R funky cracked plastic bypass fitting, new thermostat and gasket/seal (which leaks...dagnabit!).
Thanks for your continuing help! It is appreciated.

From your description, it is possible that there was no rod damage done. The coolant entering the cylinder would first foul the plug causing the rough running, then as the piston tried to pump out the coolant through the valves, that would slow the engine, and maybe stop it before any serious damage occurred. I would suppose that the more suddenly the engine stopped, the more likely you would find a bent rod. Still, the forces here are really gigantic in terms of one connecting rod stopping a running engine, even at idle.

It is all a matter of degrees. If you have a bent rod, the worse it is, the more quickly it will damage the crank. If you did not bend a rod at all, you will have no problems. The compression check is just a means to discover a problem before it becomes a bigger and more expensive problem. It would be possible to change one connecting rod with the engine in the car for the cost of a cylinder head gasket, oil pan gasket, one rod bearing and one connecting rod. (I'll bet you could find a serviceable rod here on BC cheap.) The gaskets you just installed could most likely be re-used with no problems. That could maybe be done for $100-$150. If the crank is damaged, the engine will have to come out, and you will be looking at $400 -$500 to put it right.

I don't know of a cheaper or easier way to check this out than a compression test. You can buy a tester for about $20.

Thanks Bill. I'll check that compression today and post my findings.
A million thanks.

Well, here's the latest. I've not yet done a compression check yet BUT, After replacing the LIM gasket and seals, the cracked plastic bypass fitting and replacing the thermostat and fixing a weeping leak around the thermo housing (I'd missed scraping old gasket crust from the housing, once done and resealed, leak was no more) and also throwing in some new spark plugs. I can now say that I cant see any coolant leaking anywhere. I filled the coolant resevoir to the correct level and I'll keep a close eye on it. I drove about 6 miles, varied the speed quite a bit and let her sit and idle for about 10 mins. No leaks, no overheating. It runs and sounds great. Exhaust appears normal, not whitish and sweet smelling as it had been. I'm gonna drop the cheapo oil and replace with Mobil 1 tommorow.
The only negative is that the check engine light came on and the idle became a bit rough momentarily a couple of times. Any idea why that might be occuring? I feel like I'm over the hump here thanks to the great advice. I can't thank you all enough.

Try this:

http://www.bonnevilleclub.com/forum/...e=article&k=57

And report the codes back here.

What about your O2 sensor? Fastest way to smoke one is to burn coolant.

Another point of coolant leakage (external) centers around the o-rings going into the water pump/coolant pipe fitting and the smaller coolant pipe o-ring that goes into the intake manifold. I had slight leakage for a while and those o-rings were the culprits. (And no, for some strange reason they did not get replaced during the rebuild). Though external leakage may not be your problem now, it may be in the near future since you tore into the top end.

Hey Sand,
I was just checking out the possibilty of a wasted O2 sensor. I'll bet you're right. I'll have the counterjockeys at Advance Auto throw a code reader on it and see if it is indeed the O2 sensor. I would be thrilled to spend another $35.00 to get a new one and be done with my coolant burning days!

Do NOT buy a Bosch or low-grade sensor. You'll be replacing it very soon.

Spend the money for a Denso or AC Delco only. Our experience on this has been proven time and time again.

Let's have the codes. Check the link I posted above. You can pull your own codes. You don't need a store to do it, and bias you with what they want to sell you.

Well, I threw a new O2 sensor in, tried to get Delco or Denso, Advance had neither in stock. BUT they sure did have the Bosch in stock ! I groaned and bought it. Wasn't cheap though, 54.00. I saved receipt to go back on 'em if it fails within a year.
The car ran great all weekend, no leaks, no heat buildup...all was good. Went out this morning to start her and noticed a puddle of coolant on driveway and a pretty good drip feeding it after it ran for a minute. I don't know where the external leak could be! Very frustrating. I'm gonna go try to locate it now. I'll post my findings. If anybody k nows a suspect place to check please advise.
Thanks.

Try those O-rings out. But don't go to the dealer...instead get the o-rings from Advance/Autozone. In the "help" section, there should be an assortment of O-rings in a blister pack. Clean both your metal pipes (one going to the water pump, other goes into the intake manifold...and this is NOT the metal pipe fitting mentioned earlier (that goes to the top of the water pump). Slip on the best fitting o-ring you can find, and lightly coat with blue RTV. Reassemble (make sure all the coolant ports are dry first) and let sit for a an hour or so. Refill, start, let it come up to operating temp.

Another thing...did you properly torque the intake mani down?

Good idea, but my leak is definitely originating on the driver side. Appears to be just under the throttle body. The accesory side with the water pump is dry as a bone.

Yeah, I torqued mani bolts in sequence working from center outward. Don't own an inch/lb TW so I used judgement on torque. Definitely did not overtorque, just snugged then a lil' more.

Under the TB eh? Could be the TB gasket itself, or maybe the temp. sender since it is on that side of the manifold.

Did you think to clean the threads off the intake bolts, chase the threads on the heads, and loctite? There are a few places where if the manifold isn't tight enough, it will seap coolant out (when I first did mine, I neglected to clean, loctite, and torque properly. After running for a few minutes, coolant started steadily dripping from the front driver side, near the thermostat housing. Those bolts backed out and would not hold their torque at all unless cleaned and loctite coated)

OK, I just came from the garage...this is getting weird. I removed the throttle body to better observe where leak was coming from. There is a sensor right below the TB in the manifold...not the temp sensor right beside the mani bolt on firewall side, but right above the TB bracket bolt...dont' know which sensor it is but when I was blowing some air to dry off around it, I noticed that when air entered the plastic plenum in a small round opening just below the main plenum throat, (now exposed w/ the TB removed) coolant dripped out the a similar opening just under the throat on the other side, the firewall side. When I blew air directly in this opening - coolant flowed out of the opposing hole. Is this normal? I didn't think any coolant was supposed to be present in the L27 upper plenum???
BTW - yes, cleaned all bolt threads and whatnot...this appears to be where my leak is originating.

Looks like the dripping coolant is coming from the bottom side of the throttle body. I took the TB off, smeared RTV sealant on both UIM and TB mating surfaces and reassembled. There was no gasket present here when I first disassembled, just the silicone bead on the UIM. Let sit for a few hours and started it up after idling for a couple of minutes, the drip started again in the same spot. After searching this great site, found some info explaining that the TB has a "chin" that gets coolant thru the UIM...precisely where mine seems to be leaking. Is it possible that the UIM is cracked? When I visually inspected it, it looks fine. The one stud on the UIM is a bear to tighten. It goes thru a TB brkt bolted to LIM. I may not be getting a good seat on that? I'm ready to curl up in corner and have a good cry. Has any body dealt with this before? I kinda think its something to do with that nasty 3rd UIM/TB bolt?

Sorry I didn't get here before. The silicone bead in the UIM is the gasket for the TB. Pull it out and clean it off.

If the leak is coming from the TB/UIM you probably need to clean the gasket. Reinstall with a bead of RTV Blue on both sides. This gasket is dealer only and expensive. The sleeve the TB stud goes into has flat portion on the backside. Hold it with a combination wrench. The lowest bolt on the TB can be easily done with a 13mm socket, a 3/8 U-joint, a 12" wobble extention and a 3/8" rachet.

If the leak is coming from the UIM/LIM you need to pull the UIM and fix the leak at the O-ring surrounding the TB Coolant ports.


My TB leak pissed me off so I tapped the holes in the LIM and installed 1/2-13 plugs in the ports. Look at the UIM TB mounting face for cracked plastic allowing the gasket to twist.

Thanks Dame. I've obtained the gasket for the TB...I stupidly did not realize that this was a replaceable gasket. I'll remove the TB and pull that gasket and replace w/ the new one. The only leak visible is a steady drip from bottom of TB, I can see it dripping on a sensor directly underneath. I'm hopeful that this will cure my problem. I understand your directions for getting at the lower rear TB stud, but does the stud just go thru the TB bracket (longer end 1st) then just thread into the UIM? Seems like the bracket prevents the TB from fully seating against the UIM? I'll make sure that I prevent the sleeve from turning per your advice. Might just be my own ignorance but I wanted to be sure that I'm installing this the correct way.
Thanks!

That's how mine leaked and it was a degraded UIM allowing the gasket to twist.


The lowest bolt on the TB is somewhat tricky. The TB attaches straight to the UIM, but the three holed bracket goes over that stud, then a nut to retain it. Should be the long end of the stud into the UIM.

Well, I think I finally have got the leak sealed. I had to loosen the nut on the bracket located just below the TB where the stud passes thru. This allowed the bracket to draw in just enough to allow the TB and UIM to seal. Now all is dry and life is good.
This site is a great resource and I appreciate all the help. Thanks! :)