Might Be Rear Main Seal Replacement Time?

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Aug 9, 2007
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805
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Tucson, AZ
Hi guys. I've been keeping an eye on a chronic oil leak for a while now. I'm sure the majority of it is from the rear main seal, but the oil pan edge is also staying wet despite gentle snugging. The primary drip is from the bottom of the front of the A440 (not ATF). I see this leak after a drive, and it ranges from a puddle around a dime in diameter to over an inch. The leak settles down once the vehicle is not running.

I have examined the side push rod cover and gallery plug. The plug is secure with no weeping. The cover has a very mild overall leak, but not wet. I've cleaned up that area well and monitored for a while now. Valve cover also does not appear to be leaking in any significant way. So I'm left with the rear main seal and pan gasket as the primary leak concerns...right?

I've been researching the site and using this good thread to help me analyze and decide whether to have this done or not. The job is too much for my old injuries/disabilities to tackle. I am comfortable with my Firestone guys doing these since they've been working on this vehicle for a couple of decades successfully. The biggest task they have done is the front knuckles using Kurt's kit I provided. They did a great job. They do main seal jobs commonly, but have not done a 60-series. The manager is very knowledgeable and responsible. He has quoted a very good price to do both using OEM parts. I'm comfortable with them for these reasons, but also because they are a national company that stands behind their work. That's been tested multiple times, and they step right up without hesitation. I can't speak for other FS shops, but this one is terrific. They have an affinity for the Cruiser, and since it is not a daily driver, I never rush them. They dedicate a bay and work on it until they complete. This might take a few days, but I'm okay with that.

We plan to put the vehicle up on a rack this weekend to get a good look at things and finalize a plan. I provide the FSM for them. I cannot find the specific procedures for the rear main seal replacement in the FSM. Can you guys direct me to that...or perhaps a link to a good post here? We often used posts here as guidance for work.

Any other tips or words of wisdom would be appreciated. Thanks.
 
Joined
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Messages
2,064
Location
Boulder, Co
Hi guys. I've been keeping an eye on a chronic oil leak for a while now. I'm sure the majority of it is from the rear main seal, but the oil pan edge is also staying wet despite gentle snugging. The primary drip is from the bottom of the front of the A440 (not ATF). I see this leak after a drive, and it ranges from a puddle around a dime in diameter to over an inch. The leak settles down once the vehicle is not running.

I have examined the side push rod cover and gallery plug. The plug is secure with no weeping. The cover has a very mild overall leak, but not wet. I've cleaned up that area well and monitored for a while now. Valve cover also does not appear to be leaking in any significant way. So I'm left with the rear main seal and pan gasket as the primary leak concerns...right?

I've been researching the site and using this good thread to help me analyze and decide whether to have this done or not. The job is too much for my old injuries/disabilities to tackle. I am comfortable with my Firestone guys doing these since they've been working on this vehicle for a couple of decades successfully. The biggest task they have done is the front knuckles using Kurt's kit I provided. They did a great job. They do main seal jobs commonly, but have not done a 60-series. The manager is very knowledgeable and responsible. He has quoted a very good price to do both using OEM parts. I'm comfortable with them for these reasons, but also because they are a national company that stands behind their work. That's been tested multiple times, and they step right up without hesitation. I can't speak for other FS shops, but this one is terrific. They have an affinity for the Cruiser, and since it is not a daily driver, I never rush them. They dedicate a bay and work on it until they complete. This might take a few days, but I'm okay with that.

We plan to put the vehicle up on a rack this weekend to get a good look at things and finalize a plan. I provide the FSM for them. I cannot find the specific procedures for the rear main seal replacement in the FSM. Can you guys direct me to that...or perhaps a link to a good post here? We often used posts here as guidance for work.

Any other tips or words of wisdom would be appreciated. Thanks.
They have to pull the transmission and flywheel. It will pop right out and back in in short order. They might as well do the oil pan too while they’re at it. Use a one piece oil pan gasket from Toyota and a rear main from Toyota.

Have them review the transmission, and flywheel removal procedures in the Toyota fsm. If I recall, a 4” or a 6” pvc end cap is the right size to tap that rear main back into place.

I’ve only ever pulled a manual transmission from these trucks so I’m sure the procedure for the auto is slightly different. Either way the biggest part of the job is pulling the trans and flywheel.
 
Joined
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Messages
805
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Tucson, AZ
They have to pull the transmission and flywheel. It will pop right out and back in in short order. They might as well do the oil pan too while they’re at it. Use a one piece oil pan gasket from Toyota and a rear main from Toyota.

Have them review the transmission, and flywheel removal procedures in the Toyota fsm. If I recall, a 4” or a 6” pvc end cap is the right size to tap that rear main back into place.

I’ve only ever pulled a manual transmission from these trucks so I’m sure the procedure for the auto is slightly different. Either way the biggest part of the job is pulling the trans and flywheel.
Yes, would do both using Toyota OEM parts. Thanks for the tip on the PVC.
 
Joined
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Messages
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I said I don't have a specific leak around the push rod cover, but I must correct that. It appears that I do have a bit of a leak around the forward most 2" or so. Perhaps while it's up on the rack, we can check to see if the two bolts up there are not snug. If not, we'll carefully snug them to our best estimate of the FSM torque spec for them to see if that helps.
 
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I said I don't have a specific leak around the push rod cover, but I must correct that. It appears that I do have a bit of a leak around the forward most 2" or so. Perhaps while it's up on the rack, we can check to see if the two bolts up there are not snug. If not, we'll carefully snug them to our best estimate of the FSM torque spec for them to see if that helps.
Just replace them. They’re cheap enough. NAPA carries them along with the valve cover gasket. I haven’t had any real issues with them since I installed them a few years ago. I think they’re called “valve cover grommets”
 
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Just replace them. They’re cheap enough. NAPA carries them along with the valve cover gasket. I haven’t had any real issues with them since I installed them a few years ago. I think they’re called “valve cover grommets”
I'm not sure what "them" you are talking about. The push rod cover gasket and valve cover gasket? If you're talking the push rod cover gasket, its the difficulty of the task that causes me to refrain. Daunting!
 
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I'm not sure what "them" you are talking about. The push rod cover gasket and valve cover gasket? If you're talking the push rod cover gasket, its the difficulty of the task that causes me to refrain. Daunting!
Oh! I misread that! Lol yeah pushrod cover is a bit more intense. If you go through the effort it’s worth replacing all the bolts that hold it on. If they’re rusty and worn out they might leak. I have one that has a very small trickle. You can try to snug them up gently. It worked for me a few weeks ago. If you’re not dumping oil from that spot you’ll be okay. Just keep an eye on it.
 
Joined
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Messages
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Oh! I misread that! Lol yeah pushrod cover is a bit more intense. If you go through the effort it’s worth replacing all the bolts that hold it on. If they’re rusty and worn out they might leak. I have one that has a very small trickle. You can try to snug them up gently. It worked for me a few weeks ago. If you’re not dumping oil from that spot you’ll be okay. Just keep an eye on it.
Whew! That was close! lol I would say mine is less than a trickle; just enough to show some wetness in the front 2" around the cover...mostly below it. We'll try snugging them up gently, clean up the area, and keep an eye on it.
 
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To confirm where the leak is coming from you can add ultra-violet dye to the crankcase and get a inexpensive UV flash light and use it to find the leak.
GM dealers used to have this product and instructed their dealers to use this product and process to identify engine oil leaks.
 
Joined
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Messages
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To confirm where the leak is coming from you can add ultra-violet dye to the crankcase and get a inexpensive UV flash light and use it to find the leak.
GM dealers used to have this product and instructed their dealers to use this product and process to identify engine oil leaks.
Great idea! Thank you.
 
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Messages
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To confirm where the leak is coming from you can add ultra-violet dye to the crankcase and get a inexpensive UV flash light and use it to find the leak.
GM dealers used to have this product and instructed their dealers to use this product and process to identify engine oil leaks.
I’ve been meaning to try this out... sounds super cool
 
Joined
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Messages
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It appears the UV oil dye may have been a very valuable test. The most leak is near the junction of the oil pan gasket and rear main seal, but it appears to be forward of the rear main seal. We pulled that little cover on the tranny just below the junction where oil would pass if the rear main was leaking. Nothing in there was wet. There was no fluoresce in the region nearest the rear main seal. That rear main seal was replaced with tranny rebuild about 35K ago; should be okay. We saw a little of the same at the front of the oil pan, but less. So verdict is move forward with oil pan gasket replacement.

Fingers and toes crossed.

No fluoresce around valve cover or pushrod/side cover. Pretty sure there is a slow old one at the forward three inches or so of the pushrod cover. Will carefully snug.

I guess I have some spare parts now (rear main seal, valve cover gasket, pushrod cover gasket.).
 
Joined
Mar 4, 2016
Messages
2,064
Location
Boulder, Co
It appears the UV oil dye may have been a very valuable test. The most leak is near the junction of the oil pan gasket and rear main seal, but it appears to be forward of the rear main seal. We pulled that little cover on the tranny just below the junction where oil would pass if the rear main was leaking. Nothing in there was wet. There was no fluoresce in the region nearest the rear main seal. That rear main seal was replaced with tranny rebuild about 35K ago; should be okay. We saw a little of the same at the front of the oil pan, but less. So verdict is move forward with oil pan gasket replacement.

Fingers and toes crossed.

No fluoresce around valve cover or pushrod/side cover. Pretty sure there is a slow old one at the forward three inches or so of the pushrod cover. Will carefully snug.

I guess I have some spare parts now (rear main seal, valve cover gasket, pushrod cover gasket.).
Not a bad deal!
 

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