I have a had transmission oil pump. Do I need to rebuild the whole tranny now or can I just replace the pump?

Posted by Blu_yello_husky@reddit | askcarguys | View on Reddit | 20 comments

Just bought a mechanic's special old lady's car from Utah, seller said it does not move and makes noise. I figured out within a day that it's a bad pump (it's got the death whine). The fluid is dark and overfilled but does not smell burnt. I've seen some guys on youtube replace the pump only and nothing else, is that OK to do on a 140k mile car? I plan on taking the pan off and checking the magnet for metal and clutch material to make sure, but assuming it's good, is a pump only replacement an alright thing to do? I'm fairly well versed in transmissions but I've never took one out of a car and put it back in without doing a complete overhaul, and I've never had to replace a pump either.

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20 Comments

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stlmick@reddit

I would take the pan off, clean the magnet and screen and put new fluid in regardless. I don't buy into "the metal grit is holding the gears together". If it's that bad, it's already done, and I'll put Lucas in before old fluid. I would do that before removing it to change the pump. See if it does anything. If you're well versed in transmissions, you know better than most here, and you saw it. Is it worth the time and effort gamble?

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Alternative-Purple29@reddit

"I don't buy into "the metal grit is holding the gears together"." Neither do I!

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Blu_yello_husky@reddit (OP)

It all depends on how much sludge is on that magnet really. If it looks like it's toast, it'll be getting a full rebuild. That should give me a chance to replace some of the weaker components with improved ones anyway

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Mummbles1283@reddit

Please don’t put anything but the proper fluids in it… Lucas is for junk you don’t intend on fixing properly, or driving for very long…

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NBQuade@reddit

I wouldn't do shit till I hooked it up to pressure gauges and and see what the pump is doing. You're just guessing the pump is bad at this point. I like the idea of pulling the pan and checking the filter for metal and debris too. What kind of transmission is it? Conventional or CVT? Wear will depend on how the fluid was changed. I checked the pump in a 150K miles Lexus which had poor maintenance and the pump was worn to the limit. When I pulled another Lexus pump with 250K miles but had been maintained, clearances were still good.

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Blu_yello_husky@reddit (OP)

>You're just guessing the pump is bad at this point I don't have that equipment and neither does my shop >What kind of transmission is it? Conventional or CVT? 4T65E GM the pump is clearly being starved of fluid, probably from lack of maintenance and a dirty tranny filter restricting fluid flow to the pump. I'm hoping it wasn't driven like this much because the clutches shouldn't be burnt up if they were never engaged

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NBQuade@reddit

[https://www.amazon.com/OTC-Tools-5610-Trans-Eng-Tester/dp/B000R5G0DO/](https://www.amazon.com/OTC-Tools-5610-Trans-Eng-Tester/dp/B000R5G0DO/) $100 for a 1/2 way decent one. You can get a Chinesium one for $20-30.

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Mummbles1283@reddit

Oh, totally pull that apart, at a minimum check the solenoids in the valve body, they were extremely common to burn up.

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mechshark@reddit

Wait an old lady car that is stick? Lol 😂

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Blu_yello_husky@reddit (OP)

It's not stick, who said stick?

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mechshark@reddit

The post mentions a clutch

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Blu_yello_husky@reddit (OP)

There are several clutches in an automatic transmission. Even if it was stick, there are plenty of old lady stickshift cars. Ever heard of a plymouth valiant?

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mustang-GT90210@reddit

Pumps don't just burn up. They're a symptom, not a cause, normally. I'm assuming heavily here, based on my 6F35/6F55 knowledge, knowing that the 6T family of GM transaxles are very similar. In my experience, a pump is only damaged by lack of fluid, and/or contamination. Filters don't clog on transmissions that are still in good shape. Regardless of my thoughts on pump failure, you have to drop the trans, and split the cases, in order to replace the pump and filter. Why would you not at least do a soft part rebuild at that time? It's only a couple hundred dollars more, and could save you 2 weekends of time.

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1morepl8@reddit

I suffer from the same logic and then my 5k overhaul is a 20k overhaul.

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MrBlandEST@reddit

You don't have anything to lose except your labor and the cost of a pump. Worth a shot. If it doesn't work you get to pull it again.

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Blu_yello_husky@reddit (OP)

Not the funnest thing to do. This is my first transaxle. I really don't want to deal with dropping the whole cradle twice and removing both half shafts and front hubs

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MrBlandEST@reddit

I wasn't thinking front wheel drive. Much less work with a rear drive.

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Blu_yello_husky@reddit (OP)

Yes, I know, I've done many of them. Takes 3 hours on the ground with a jack, less than an hour with a hoist

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Mummbles1283@reddit

If you’re willing to open it up for a pump it’s not much more work to just go through the clutches and planetary gears. Transmissions are stupid simple… the valve body is black magic but the rest is simple.