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97 Transport: Transmission (P1870) Problems

1997 Pontiac Transport with 185,000 miles.

A month or so back, I started getting a 2-3 second squeel that sounded like a slipping belt that eventually engaged at the end of the 2-3 second squeel. I noticed the power steering was dripping onto the Serpentine belt and dismissed the problem as a slipping belt. Then on a subsequent trip down to South Carolina, the Service Engine Soon (SES) light appeared and the tranmission would no longer lock up the torque converter.

Autozone found two (2) error codes, both of which were P1870.

After surfing the web last night I found a bunch of info on the P1870 that had to do with slipping Torque Converter Clutch (TCC) problems. Most of the posts had to do with Chevy Trucks, not minivans. It appears that GM replaced cast iron their valve body with Aluminum and suffered loss of wear resistance. Apparently the valve gets worn and fails to generate proper pressure to the TCC, and causes it to slip. Last evening I pulled the PowerTrain Control Module (PCM) fuse in effort to clear the code. This didn't work, but this morning I once again experienced the 2-3 second squeel as the TCC tried to engage.

I have called the Transmission shop and they are quoting prices from $800 to $2000. I am about ready to sell the minivan for $2000-2500; hence, this sort of investment seems foolish.

Questions:

1) Is the TCC probably toast? 2) If I replace the Torque converter ($119 at Autozone) will I also be replacing the TCC? 3) How much of an effort is it to replace the torque converter on a 97 transport? Do I have to remove the tranny onto a bench? 4) For the valve body, I see there are several companies that make a "Bore & Sleeve Kit." Anyone have experience with this kit? What special tools are required? How much of an effort to get the valve body out so it can be bored and resleeved? 5) Is there any wisdom in rebuilding the valve body first and then replacing the torque converter only if the problem persists? (Does it make far more sense to replace both while I'm elbow deep in the tranny? (remember, I am going to resell this soon and I want to be honest as to what I have repaired)

Thanks in advance. Justin

Reply to
Justin Koch
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Sounds like you're going at it from the wrong angle. If a worn bore in the valve body is not allowing enough pressure to fully engage the TC clutch, then replacing the converter is not going to fix that. You need to be looking more into replacing the valve body, or possibly boring/sleeving (if even possible) the worn bore in the one you have. Depending on how long you have been driving it like that, the existing converter may work normally if it starts getting sufficient pressure from the new or repaired valve body. On the other hand, if it is has been doing this a long time, it may be toast and will need to be replaced as well.

Lee Richardson

Reply to
Lee Richardson

I had the trans on my '94 rebuilt last summer/fall. There is a bulletin out about the lockup control valve body wearing and sticking on these trans IIRC. The rebuilder boared and resleaved the valve with a steel sleave - said it should never give problems again (trans ONLY had about 320,000km on it when the "drive tube" inside lost it's teeth, necessitating the rebuild)

Reply to
nospam.clare.nce

Lee,

I agree with you (see #5 below)

Do you know how deep I have to dig to get to the valve body? Can I get to it once I have removed the pan? Do I need to remove the tranny from the minivan?

Thanks! Justin Koch

Reply to
Justin Koch

A new valve body (if available) would probably cost more than the converter, but should be easier to change. Boring and sleeving sounds like a good solution, but may require tools and skill a novice may lack. While I am not familiar with your particular model, usually removing the oil pan exposes the body, and it bolts to the transmission case. There may well be metal tubes, wiring connectors, or other fragile parts attached.

Lee Richardson

Reply to
Lee Richardson

If memory serves me, the valve body is not located inside the drives side end case of the the transmission, not under the transmission oil pan.

Mike

Reply to
scogod2003

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