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 Post subject: 1996 SSEi
PostPosted: Tue Aug 22, 2017 11:00 am 
Certified Bonneville Nut
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Joined: Tue Aug 25, 2009 8:32 pm
Posts: 4484
Location: Dearborn, MI
Year and Trim: '93 SSEi
'05 STS-4
'97 Camaro
'97 LeSabre
This is a mini-project I took on to engine swap a motor that had low oil pressure due to a bad cam bearing. Unfortunately, I don't have the capability to R&R cam bearings, so for me repairing that engine is going to require machine shop work. They won't touch the engine unless you tear it down and clean it up first, so all said and done it's a minimum $1000 project.

So I looked around and found a low mileage 3800 for $400. I figured it would need LIM gaskets, then drop it in and go. Sounds like a plan, right?

Ready for surgery!

Old motor stripped and ready to pull:



And it's out!

Inside the timing cover, where the last of the bearing material resides:

New engine, torn down and cleaned up, ready for new gaskets:

Yup, knew that was going to look like that:

New gaskets:

Engine back together again:

Going back in!

The engine in it's new home:

Job's done!

I couldn't tell you why, but every time I worked on that engine I got the feeling like somebody has either had it out already or it wasn't the original for the car. There were a few bolts that were over-tightened, and the b*** bolt was missing... No reason to take that particular bolt off unless you're separating the engine from the trans. The vacuum lines were a mess with extra lines with screws blocking them off, etc... My bet is that the combination of the bad balancer knocking around and the low oil pressure the previous owner offloaded the car before it died completely.

But that doesn't matter. What does matter, is starting the car! The replacement motor came from a W-body, so all the brackets and harness had to be swapped over, and because the '96 has the 4t60 the TCC bolt holes had to be re-drilled to match (easier than swapping flex plates and replacing TTY bolts.) But everything was back in place, all the missing bolts replaced, the battery connected...

And it started right up, as if it had never sat on a dusty shelf for a year! Idle was a little rough though, I figured that maybe a spark plug was bad (the ones on the replacement motor looked new so I didn't touch them). As soon as you revved it up past idle the misfire cleared up, so I'm thinking at that point that one of the cylinders sat with a valve open, a few minutes running and the valve should seal back up again.

Road test showed it was making full boost, and pulled hard, but the misfire at idle persisted. So, it's not timing or fuel or spark. It has to be compression. I pulled the car back in the garage, with it still warm pulled the plugs and started the leak-down test. Cylinder #3, which I had previously determined was misfiring (by pulling the ignition wire), was up first. Set the piston to TDC, and let the air flow. A healthy cylinder usually leaks 10-15%. This cylinder, testing done at 90 PSI, only held 15 PSI. That's 84%. Leaking into the intake. I moved to check cylinder #1, it held 20 PSI... again, out the intake. #5 was at 40 PSI, out the exhaust. Results that bad mean I have no choice but to check the other bank too. Cylinder #6 turned out to be 82 PSI, #4 83 PSI, and #2 was 90 PSI.

I guess at least I knew I didn't have to pull the rear head off! But these engines were "Tested as running and allowed to idle for 45 minutes to verify they had no issues before being pulled". I shouldn't have had to do anything...

So I drained the coolant, and pulled the front head off. Found it had cracks in #1 and #5, and I could see light through the #3 intake valve, likely slightly bent. Luckily, the yard I got the motor from had a pair of heads in stock, so I took it back to them and worked out a deal to swap out the cracked head for a good one.

But you know me, once I get into something this far I'm not going to put that head on the motor without pulling it apart and checking it, I don't want to have to pull it again. So I disassembled it, it looked like the valves were sealing, but the exhaust valves were pitted. The intake valves appeared OK, so I chucked them into my drill and found that one of the intake valves was bent. I guess at least the head isn't cracked, right? I can't use a bent valve, so I got some new ones and got the lucky task of lapping in the valve seat for the bent valve. I say lucky, but it really means that the valve seat in the head is not true anymore, it's worn to match the bent valve, and is going to take some elbow grease to get it to seal again. Then of course, the pushrods had worn into the rockers on this bank..

It's crazy how such a small imperfection could cause a misfire:

Head out, new head gasket ready:

Rockers! Left to right - pushrod worn out - 5/16 ball nose mostly cleaned up - no wear

Lapping the valves:

Guess what? The cylinder with the bent intake valve also had a bent exhaust valve!

Nothing even more elbow grease can't handle...




Finally, back together again, and back on the motor. I chose to do the leakdown test before I put anything back together... #1 was 84 PSI, #3 79 PSI, #5 81 PSI. 12% leakdown is acceptable, so everything can go back together!

Finished up, started the car, and no more misfire. I celebrated by burping the coolant system and taking it home, then of course, grabbing a beer!

Blow all the things! Wait, I meant boost. Boost!

'93 Pontiac Bonneville SSEi - Twincharged, manual, and lots more! Build thread
'97 Chevy Camaro - 3800 supercharged, T5, T-tops
'05 Cadillac STS - V8, AWD, her DD
'92 Olds Trofeo - Fair weather DD
'84 GMC Sierra Classic - Twin turbo 3800
'97 Buick LeSabre - L67 winter DD
'92 Pontiac Bonneville SSE future project

Doesn't run:
'87 Buick LeSabre T-type - future victim
'67 Buick LeSabre - future victim

 Post subject: Re: 1996 SSEi
PostPosted: Wed Aug 23, 2017 8:46 am 
Posts like an L67
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Joined: Wed Jul 14, 2010 9:15 pm
Posts: 1469
Location: Palm Bay, FL
Year and Trim: 1999 Buick Lesabre Custom
Wow, that sounds like quite the unexpected headache for what should have been a quick and easy project for you! Glad to see it back on the road again. I agree that it sounds like the P/O tried to bandaid it before it died an inevitable death.



Current: 2013 Infiniti G37 Journey
1999 Infiniti G20T - Sold
1999 Buick Lesabre - Race Couch - gone but not forgotten

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