Oil pan gasket replaced now main seal leaks

[ladorn45]

Hey everyone.

Want to get your opinion. Took my 01 tahoe to get a small oil leak fixed and they told me that the oil pan gasket was leaking and that it was not the main seal. Theu fixed the gasket and it is still leaking and now saying its the main oil seal leaking. Is it possible that after replacing the gasket on oil pan they did somethi g to cause the main seal to leak

 

[justirv]

Hey everyone.

Want to get your opinion. Took my 01 tahoe to get a small oil leak fixed and they told me that the oil pan gasket was leaking and that it was not the main seal. Theu fixed the gasket and it is still leaking and now saying its the main oil seal leaking. Is it possible that after replacing the gasket on oil pan they did somethi g to cause the main seal to leak

I wouldn't think they are related unless you're having a PCV block pressurization issue. Definitely check the oil cooler block-off plate (by oil filter) which tends to warp and leak. Pull the bellhousing inspection cover to check for oil from RMS. The oil pressure sensor, cam sensor, valve cover gaskets, and rear engine cover can all be suspect for oil back there. Also, did they replace the oil pump or O-ring while doing pan gasket (preventative measure)?

 

[ladorn45]

From my knowledge just only the oil pan gasket. They did a dye to track the leak amd tild me that its coming from the gasket i asked if that required them to drop transmission and he said no because that would only be for the main seal which was not leaking according to them at the time. So you dont think its something they caused and was more of them missing it

 

[strutaeng]

More than likely it was the RMS (or RMS AND oil pan gasket) leaking and they only saw the oil pan gasket leaking.

The RMS is really hard to diagnose even with the dye, in my experience.

 

[ladorn45]

Thanks for all your help

 

[OR VietVet]

Doing the oil pan gasket will not cause a RMS to leak. The RMS is accessible with transmission unbolted and moved back or removed completely. None of that has to be done to do an oil pan gasket. If the PCV system is clogged up, the oil leak will always start and be at the weakest sealed area. That can be oil pan, valve covers, intake, oil sender, oil cooler lines plate or block off plate or even the RMS. The RMS MAY have been not leaking but was the next weak link in all the oil seal areas I mentioned.

When you start "chasing oil leaks" you need to be ready for whatever comes down the pike.

 

[West 1]

The Rear Main Seal is mounted in an aluminum plate that bolts to the rear of the engine, it attaches to the oil pan at the bottom and has a gasket that can fail. It can leak right at the connection of the oil pan and this gasket. The repair is the same, the rear main seal has to be replaced. I have repaired several LS engines with oil leaks. Just did my 08 Yukon last week which ended up being an actual rear main seal leak. The gasket on mine was fine. Most I have repaired I found the gasket was leaking not the seal.

I was speaking to a friend that owns a Machine Shop last week as I had my engine apart. He said he has seen some where a crack develops in the factory aluminum plate that the RMS is mounted in. He said the replacement GM plate is thicker and stronger and does not crack. GM is said to have a bulletin out on this issue. I have not seen a cracked plate yet. He said a new GM plate with the improved design is available for around $60 and comes with the new RMS?

I can’t believe a shop would pull and oil pan on an LS design and NOT install a new Oil Pump Oring. With the pan off it is a $5.00 part and 10 minutes of work that could save you $600 later?

 

[ladorn45]

Thanks for the info. Yea originally i brought it in because i saw a small leak coming from the oil filter/ and drain plug bolt. I got the car back and went under and see the same leak.

 

[justirv]

Doing the oil pan gasket will not cause a RMS to leak. The RMS is accessible with transmission unbolted and moved back or removed completely. None of that has to be done to do an oil pan gasket. If the PCV system is clogged up, the oil leak will always start and be at the weakest sealed area. That can be oil pan, valve covers, intake, oil sender, oil cooler lines plate or block off plate or even the RMS. The RMS MAY have been not leaking but was the next weak link in all the oil seal areas I mentioned.

When you start "chasing oil leaks" you need to be ready for whatever comes down the pike.

Agreed @OR VietVet, as far as PCV if the original leak was sealed at the pan, the next weakest spot would leak next.

 

[justirv]

The Rear Main Seal is mounted in an aluminum plate that bolts to the rear of the engine, it attaches to the oil pan at the bottom and has a gasket that can fail. It can leak right at the connection of the oil pan and this gasket. The repair is the same, the rear main seal has to be replaced. I have repaired several LS engines with oil leaks. Just did my 08 Yukon last week which ended up being an actual rear main seal leak. The gasket on mine was fine. Most I have repaired I found the gasket was leaking not the seal.

I was speaking to a friend that owns a Machine Shop last week as I had my engine apart. He said he has seen some where a crack develops in the factory aluminum plate that the RMS is mounted in. He said the replacement GM plate is thicker and stronger and does not crack. GM is said to have a bulletin out on this issue. I have not seen a cracked plate yet. He said a new GM plate with the improved design is available for around $60 and comes with the new RMS?

I can’t believe a shop would pull and oil pan on an LS design and NOT install a new Oil Pump Oring. With the pan off it is a $5.00 part and 10 minutes of work that could save you $600 later?

The Rear Main Seal is mounted in an aluminum plate that bolts to the rear of the engine, it attaches to the oil pan at the bottom and has a gasket that can fail. It can leak right at the connection of the oil pan and this gasket. The repair is the same, the rear main seal has to be replaced. I have repaired several LS engines with oil leaks. Just did my 08 Yukon last week which ended up being an actual rear main seal leak. The gasket on mine was fine. Most I have repaired I found the gasket was leaking not the seal.

I was speaking to a friend that owns a Machine Shop last week as I had my engine apart. He said he has seen some where a crack develops in the factory aluminum plate that the RMS is mounted in. He said the replacement GM plate is thicker and stronger and does not crack. GM is said to have a bulletin out on this issue. I have not seen a cracked plate yet. He said a new GM plate with the improved design is available for around $60 and comes with the new RMS?

I can’t believe a shop would pull and oil pan on an LS design and NOT install a new Oil Pump Oring. With the pan off it is a $5.00 part and 10 minutes of work that could save you $600 later?

@West 1, I would hope they'd replace it (O-ring), but I'm not very trusting.

 

[OR VietVet]

@West 1, I would hope they'd replace it (O-ring), but I'm not very trusting.

Never ever HOPE! Tell them to do it or do it yourself, if doing the work yourself. If you have it done, ALWAYS ask for old parts.

 

[fredcook]

I have lost count of how many times someone I know said they were told by a shop their rear main seal was leaking and were flipping out because of the cost to repair it. For every one of those friends, I stuck a borescope into the bell housing inspection port and took pictures for them showing a clean dry rear main seal. It seams just about anyone that sees oil accumulating where the oil pan and bell housing meet just assume it's the rear main seal. I've put over 300,000 miles on GTM 900's, and have yet to experience a leaking rear main seal. Not saying they don't, but I think it's less common that it's made out to be.

My personal experience has been that oil accumulating around the oil pan / bell housing area has been the oil pan itself, the rear of valve cover gaskets, the oil pressure sensor, dip stick tube ingress, and the cooler block off plate. Not necessarily in that order. Oil coming from these sources will accumulate where the oil pan and bell housing come together because it's the lowest point and oil naturally moves back with the vehicles forward motion, air circulation, etc.

 

[OR VietVet]

Anyone that thinks they are saving money by stretching out oil change intervals to a full year, will pay for that savings by a 50/50% chance of a RMS leak. Should be using synthetic oils and a quality filter. If you change vehicles every 3 years, stretch out the oil change interval all you want.

 

[TahoeRestore]

If you're still dealing with the leak, you may want to check out my latest thread. Not solved, but getting close.

 

[ladorn45]

If you're still dealing with the leak, you may want to check out my latest thread. Not solved, but getting close.

Thanks waiting for it to get warmer and my neighbor who is a retired mechanic is gonna help me find it

 

[LsHart]

I'm surprised they didn't say both was leaking or say need to do one then see if the other is leaking. Cause if it has miles on it, it's probably leaking. If it hasn't been fixed already. Just my 2 cents.

 

[ladorn45]

Yea not a fan how they handled it. I took it in cause it was a small leak like a drop or two of oil on the driveway every other day or week. They even said it was a tiny leak that i could of left it alone. But decided to do it to prevent it becoming a bigger thing. They did thier test and confirmed it was that and assured me it was not the main seal because if that was the case i would of probably held off them doing it because that would of required them removing the transmission and for that small of a leak i was more worried of creating more issues. After they reppaced the gasket and i noticed it was still leaking they then confirmed it was the main seal. When i told them that they assured me that it was nit that they then that at the time it was hard to confirm cause it was a big leak which was not the case and convinently they dont fix main seal leaks and that i would have to take it to another place.