LS Oil Pan Alignment Problems

[CJM72]

Looking for some advice here. I've destroyed my second trans pump (4l65e) in less than 500 miles. First one lasted about 450 miles after I got my swap running. My trans guy suspected a runout or an alignment problem. Flexplate seemed to have a bit of runout, so I replaced that. The trans pump was replaced, and it appears to have failed after about 50 miles since I got it all back together.

After a lot of inspection, I have a suspicion that the oil pan is sitting proud of the block by around .010". This was measured from the flexplate to the trans mounting surface (same location on the flexplate rotated around). I did have the pan off before I installed it, but I recall being careful to make sure it was a flush or slightly inset from the block surface. How can I check the alignment of the pan to confirm without any special tools? If it has been pulled back, do you think I'll need to pull the pan and fully reinstall with a gasket or will I be able to loosen it up and tap it forward?

[Joyridin]

Without knowing how much clearance from the pan to the crossmember, I can easily pull the pan off the LS engine in my car without touching the transmission. I think I removed the starter (I do not recall), the bolts holding the pan, and let it drop. When I put it back on, I used the old gasket and put some RTV in the corners and bolted it up.I think I left the bolts loose and tightened the 2 large bolts from the trans to the pan, then went around and tightened all the rest. Not hard at all.

To be honest, I highly doubt .010" is going to kill the trans pump. Maybe .050" or something, but the converter flops around in the trans more than that.

[CJM72]

I'd generally agree that it shouldn't kill the trans pump, but after 2 failures... I'm grasping at straws here. It could be possible that the torque converter has some runout, but I don't have the equipment to check that. I'll pull the flexplate and check the oil pan alignment again. On my blazer, I may have to pull my engine cross member to get it out. I'm tempted to loosen and tap forward, but I have a feeling the RTV joints might either leak or resist moving.

The major symptom is 2 failed transmissions with low miles. Pump was shattered on the first one, don't know about the second rebuild but I lost all pump pressure. Dowel pins are in, torque converter clearance was 1/8" each time, crank end play is good, runout of new flexplate is .008" max. Not sure what else to check. My trans builder is a highly respected speed and performance guy. Very meticulous and I trust he isn't doing something wrong here. But something isn't right....

[Joyridin]

Originally Posted by CJM72

I'd generally agree that it shouldn't kill the trans pump, but after 2 failures... I'm grasping at straws here. It could be possible that the torque converter has some runout, but I don't have the equipment to check that. I'll pull the flexplate and check the oil pan alignment again. On my blazer, I may have to pull my engine cross member to get it out. I'm tempted to loosen and tap forward, but I have a feeling the RTV joints might either leak or resist moving.

The major symptom is 2 failed transmissions with low miles. Pump was shattered on the first one, don't know about the second rebuild but I lost all pump pressure. Dowel pins are in, torque converter clearance was 1/8" each time, crank end play is good, runout of new flexplate is .008" max. Not sure what else to check. My trans builder is a highly respected speed and performance guy. Very meticulous and I trust he isn't doing something wrong here. But something isn't right....

I highly doubt .010" would even break the RTV seal. RTV flexes more than that.

Are you sure your torque converter isn't massively out of balance or something? Again....010" isn't going to mean anything on the oil pan.

[CJM72]

Originally Posted by Joyridin

I highly doubt .010" would even break the RTV seal. RTV flexes more than that.

Are you sure your torque converter isn't massively out of balance or something? Again....010" isn't going to mean anything on the oil pan.

I suspect that the converter could be a source of the problem. It was new when I installed the trans and my transmission builder was able to clean up the snout and we reused it this second time. I've never heard of a converter with bad runout or balance problems, but I don't have access to a lathe to check it.

I've thought of just bolting it to the flexplate without the trans, but I suspect it will just distort the flexplate due to the weight and make it difficult to get a runout measurement. I should mount it just to see how the crank fits.

[biketopia]

What is your drive shaft situation like? I would originally think you have a problem with your flex plate and converter combo as there's some differences depending on the crank and what converter you use. the snout could be be hitting the crank, pushing on the pump causing it to fail. Also happens when the converter isn't fully seated. If your driveshaft is too long it will do a similar thing and push the internals of the trans forward as it goes over bumps and eventually take out the trans and the thrust washer in the engine.

[CJM72]

Originally Posted by biketopia

What is your drive shaft situation like? I would originally think you have a problem with your flex plate and converter combo as there's some differences depending on the crank and what converter you use. the snout could be be hitting the crank, pushing on the pump causing it to fail. Also happens when the converter isn't fully seated. If your driveshaft is too long it will do a similar thing and push the internals of the trans forward as it goes over bumps and eventually take out the trans and the thrust washer in the engine.

This swap is in a 72 Blazer. The 4l65e is mated to an NP205 using their adapter kit. There is a slip collar in the adapter between transmission and transfer case This appears to bolt together easily without any interference. The pump appeared to fracture into many parts like the converter has major runout at the snout.

[biketopia]

https://ls1tech.com/forums/automatic...s-spacers.html

Here's a good thread over at LS1 Tech about the crank, flexplate, spacer, nonsense. Are you using an aftermarket converter or the stock converter from the swap?

[CJM72]

Originally Posted by biketopia

https://ls1tech.com/forums/automatic...s-spacers.html

Here's a good thread over at LS1 Tech about the crank, flexplate, spacer, nonsense. Are you using an aftermarket converter or the stock converter from the swap?

Thanks for the link, I'll check it out. Motor is a stock LQ9 pulled from a wrecked Escalade. Torque converter is not stock, but is basically a stock replacement. It was spec'd by my builder using his preferred supplier. Flexplate is correct and the torque converter spacing was dead on at 1/8". I'll read through the link to see if I'm missing something.

I mounted the torque converter to the flexplate during lunch. Pilot fit nice it bolted in without any issues. I'll check the runout when my wife can give me a hand turning the motor. Simply spinning the flexplate by hand moves things around too much to get any sort of accurate reading.

[CJM72]

Runout at the torque converter drive shaft just behind the pump drive slots is about .005". Hard to get a reading because the flexplate sort of flops around and my dial indicator mount wasn't the strongest. Seems like Torque Converter runout isn't my problem.

Thanks for all the input so far.

[mongocanfly]

I've had the oilpan off mine multiple times...I just dont see anyway possible for it to affect the trans in any way.. dont have to remove the starter and there is a dust shield,on mine ,between the flywheel and oil pan.,, mine has no rtv either,,its a 1 piece gasket for the whole pan
. I'm thinking you have internal trans issues .. was the trans, lines, and cooler,and tq conv cleaned after the 1st failure?.. could be your just pumping trash thru new parts..what does the trans filter and fluid look like?

Clinebarger still checks in time to time, maybe if you reword a post to ask about the 4l65 issues instead of oil pan he may see it.. hes the trans guru

[Accelo]

I helped a gal with her Z28 / IROC Camaro. Kept breaking the flex plate. I just kept installing new one. Finally got the OK to check the run-out . I reinstalled the transmission, without the converter. Just used a dial indicator, on the flex plate and indicator on the transmission, to inspect the run-out . Using the front pump machined surface I found it had .100 axial run-out in 10" diameter circle. Back of the block or the front of the transmission wasn't machined correctly. I put it back together and informed the customer of the issue. Never saw the Camaro again.
My point is the pump can take a horrendous amount of run-out and the bushing and pump lived.

You didn't mention your max rpm. Could it be ballooning? Crankshaft axial run-out?
You have covered all the major points. Time to replace the converter. I was wondering why it wasn't replaced when the pump failed the first time, or did I miss something? No way to keep the debris out the converter when the pump fails internally.

[CJM72]

Originally Posted by Accelo

I helped a gal with her Z28 / IROC Camaro. Kept breaking the flex plate. I just kept installing new one. Finally got the OK to check the run-out . I reinstalled the transmission, without the converter. Just used a dial indicator, on the flex plate and indicator on the transmission, to inspect the run-out . Using the front pump machined surface I found it had .100 axial run-out in 10" diameter circle. Back of the block or the front of the transmission wasn't machined correctly. I put it back together and informed the customer of the issue. Never saw the Camaro again.
My point is the pump can take a horrendous amount of run-out and the bushing and pump lived.

You didn't mention your max rpm. Could it be ballooning? Crankshaft axial run-out?
You have covered all the major points. Time to replace the converter. I was wondering why it wasn't replaced when the pump failed the first time, or did I miss something? No way to keep the debris out the converter when the pump fails internally.

Good questions Accelo. Crank end play is well within spec. Around .003” if I recall. Flexplate to block machining looks consistent. This is a stock LQ9 in a K5, so nothing crazy for rpm. Neither failure occurred at full throttle or high rpm. Just accelerated and then nothing. Starting to suspect that my spacing is just off and needs to be shimmed.

My builder inspected the torque converter and thought it looked ok to reuse. If the pump just cracked and didn’t fragment into tiny pieces, would a torque converter replacement be required? Thinking of rebuilding or replacing the pump myself with a billet rotor. Realign oil pan and triple check converter spacing. Should a replacement convert be mandatory?
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[Accelo]

If the pump just cracked and didn’t fragment into tiny pieces, would a torque converter replacement be required?
I would have reused it under those conditions. Typically they Grenade and require TC replacement. You were lucky to catch it this soon.

This is a tough one as you seem to have covered all the bases. I would likely replace the converter since their isn't an obvious cause. IMHO, Time to throw some money at it and hope for the best.

[CJM72]

Thanks Accelo. I pulled the flex plate and the alignment with the block is fine. So that theory is out. Measurements to the flex plate indicate it wasn't right but this measurement is tough to get accurately.

I'll go for a billet pump rotor and maybe a new torque converter. It looks like a stock stall converter with a sticker with TMBX 2423 8896 on it.

[truckdude239]

the best way to aligne the oil pan and according to gm is to have the transmission bolted tot eh back of the engine. the conveter should hever be reused after that kind fo failure unless it was cut apart and clean you could have a chunk of metal in the conveter that made its way back intot eh pump

[jed971959]

Hi did the convertor turn free by hand before putting in the convertor bolts

[Accelo]

I am in the process of helping out a fella right now. He didn't get his converter in all three clicks. Never pumped an ounce of oil as the converter and oil lines to the radiator were completely dry. (I want to acknowledge your issue is different as your at least ran).
Still haven't gotten the pump out to inspect the carnage. My point is they can fail in many different ways. Each has to be inspected and a decision made on the evidence. I do know he has a new GM pump to install.
Good luck.