EL CAMINO Clunking auto trans under load when warm and low rpm

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57 Handyman

Master Mechanic
Feb 6, 2017
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What is the odometer reading? More than likely, if the reading is less an 100K miles, it has flipped over since an 87 El Camino is probably a high mileage vehicle. For verification, look at whether there are components which identify how much care it has had in it's 65 year-lifetime. My guess is the transmission is in need for an overhaul. The clunking are the result of clutches first slipping then engaging. As for putting in a shift kit, depending on your plans for this classic and budget, I'd first do some research finding a local, reputable auto transmission shop that only does trans rebuilding, The best place to get a lead on a shop is at your local cruise nights and asking the participants. Good luck and keep us updated on your progress/success in keeping your 87 on the road.

BTW, I also own an 87 El Camino. The motor has been yanked and all smog/computer controls removed.
 

78Delta88

Royal Smart Person
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May 23, 2022
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Just reading through your thread, and like the others have said many things to look at. With a 305 it is probably a 2004r, but being El Camino it could be a 700r4, but more likely the 2004r. To me it sounds like broken accumulator spring or sticking accumulator.

Realistically you need to pull it and have it rebuilt. If you pull the pan you need to see how much crud has collected and any metal pieces.

Personally, I wouldn't do a shift kit with the way it is now. Doing so could actually make it worse.
 

schwim

Not-quite-so-new-guy
Nov 13, 2022
29
2
3
Coastal VA, US
What is the odometer reading? More than likely, if the reading is less an 100K miles, it has flipped over since an 87 El Camino is probably a high mileage vehicle. For verification, look at whether there are components which identify how much care it has had in it's 65 year-lifetime. My guess is the transmission is in need for an overhaul. The clunking are the result of clutches first slipping then engaging. As for putting in a shift kit, depending on your plans for this classic and budget, I'd first do some research finding a local, reputable auto transmission shop that only does trans rebuilding, The best place to get a lead on a shop is at your local cruise nights and asking the participants. Good luck and keep us updated on your progress/success in keeping your 87 on the road.

BTW, I also own an 87 El Camino. The motor has been yanked and all smog/computer controls removed.

It shows 45k on the clock. The odd thing is that there is practically no wear on the seats or pedals and under the hood looks like nothing's been altered from it's birthday. The age almost dictates a rollover on the odo but it's condition makes me wonder if it's low mileage.

Just reading through your thread, and like the others have said many things to look at. With a 305 it is probably a 2004r, but being El Camino it could be a 700r4, but more likely the 2004r. To me it sounds like broken accumulator spring or sticking accumulator.

Realistically you need to pull it and have it rebuilt. If you pull the pan you need to see how much crud has collected and any metal pieces.

Personally, I wouldn't do a shift kit with the way it is now. Doing so could actually make it worse.

I quickly decided against the kit after driving it today. Something is still terribly wrong with it. When engaged, the trans feels great but if it's not working right, it either shudders due to repeated shifting back and forth or the 2-3 has a huge rev gap between them.

I've parked it for now as I try to figure out the path I'm going to take. If the vehicle looks like a money pit, I'm going to have to pass it to another enthusiast. I don't want to get into an attempt to outspend it's issues as I don't have a lot to throw at it.
 

78Delta88

Royal Smart Person
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May 23, 2022
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Understandable as some shops can go as high as 3k or more.

I can offer to help you with a good rebuilt one, I have several 2004r units.

The accumulator springs break all the time. It's a common problem. Also at that age and even if it had 1k on the clock, most likely the piston and other seals are no good just due to age.
 

schwim

Not-quite-so-new-guy
Nov 13, 2022
29
2
3
Coastal VA, US
Understandable as some shops can go as high as 3k or more.

I can offer to help you with a good rebuilt one, I have several 2004r units.

The accumulator springs break all the time. It's a common problem. Also at that age and even if it had 1k on the clock, most likely the piston and other seals are no good just due to age.

That price would definitely knock me out of the running. I very much appreciate your offer of a rebuilt unit but I suspect the cost of getting it across the country would make it quite pricey in the end. Regarding the springs and pistons/seals, are these something I can replace with the unit in the car? I watched this video on installing a shift kit and although I wouldn't be installing that kit, would the repair process be the same if those were indeed the parts at the core of my problems?
 

ELCAM

Royal Smart Person
Jun 19, 2021
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What's the eighth digit of the VIN number?

VIN "G" the L69 305 came with the MW9 (200-4R).

VIN "H" the LG4 305 could come with the MD8 (700R4) or the MW9 (200-4R).

Also a picture of the pan or a good clear picture of the back of the engine where the transmission bolts on would help ID the transmission.

Putting a shift kit in it is just a band aid on a serious wound, likely you will need to rebuild the transmission.
You can try some diagnostics but will need a 300PSI gauge to try to determine the problem.
 

78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
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That price would definitely knock me out of the running. I very much appreciate your offer of a rebuilt unit but I suspect the cost of getting it across the country would make it quite pricey in the end. Regarding the springs and pistons/seals, are these something I can replace with the unit in the car? I watched this video on installing a shift kit and although I wouldn't be installing that kit, would the repair process be the same if those were indeed the parts at the core of my problems?
Shipping would be my biggest concern as well so thinking along same lines. I might be coming to FT Lee area next couple months so if that happens I could just bring with me.
 
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78Delta88

Royal Smart Person
Supporting Member
May 23, 2022
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To fix the issue you describe you will need to pull it.

You can pull pan and pull valve body while still in car, but the caveat is if not sure what you are doing you can cause more problems.

If you can send pic or do zoom I can walk you through it
 

pagrunt

Geezer
Sep 14, 2014
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Elderton, Pa
What's the eighth digit of the VIN number?

VIN "G" the L69 305 came with the MW9 (200-4R).

VIN "H" the LG4 305 could come with the MD8 (700R4) or the MW9 (200-4R).

Also a picture of the pan or a good clear picture of the back of the engine where the transmission bolts on would help ID the transmission.

Putting a shift kit in it is just a band aid on a serious wound, likely you will need to rebuild the transmission.
You can try some diagnostics but will need a 300PSI gauge to try to determine the problem.
The only 305 (& V8) the '87 El Camino/Caballero came with was the LG4 "H". That could of had either the (M29/MX1) TH200C 3 speed base or the TH200-4R 4 speed/overdrive (MW9/MX0) option. The A/G platform never had the TH700R4 option.
 
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ELCAM

Royal Smart Person
Jun 19, 2021
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