98 trani problems

[Silverado6.5td]

I have a 4l80e trani in my truck and recently started having problems with the OD. After the trani starts to warm up (around 150 degrees) I lose OD and it starts to shift hard from 1-2 and 2-3. When it cools down I get it back. It is starting to do this now even before the temperature starts to move the needle. The only code it has ever thrown is a P1870 (transmission component slipping).

I had it in to a trani shop and they told me that it could possibly be the speed sensor if it is still the original one, but that it has most likely been changes sice there is 325,000kms on the truck. If that is not the problem that it needs to be rebuilt. When he took it for a test drive prior to losing OD, he sais that the torque converter wasn't locking up.

So after reading up on many posts, I came to the conclusion to change solenoids A and B as well as the PCS and TCC solenoids as a starting point.

Then I read on a trani website that the torque converter clutch regulator valve can also be responsible for throwing the P1870 code.

I called another trani shop in the area asking for the TCC regulator valve kit and it is $50. He asked me what the trani was doing, so after I explained it to him, he told me that the valve kit I asked for and another valve in the valve body should be changed with the upgraded kits he has.

It is $120 for both kits, one requires tools to bore out the hole. He said he would install them for me for free.

I asked him if I should be changing the other solenoids as well while I have it apart especiallt the TCC solenoid and he said the if solenoids A or B were defective it would throuw a code for that and I would only have specific gears depending on what solenoid is defective, but since 1,2 and 3 still work fine when OD is lost those solenoids should be fine.

He also said the TCC solenoid should be fine as well, but he would do a resistance test on it to see.

I value everyone's opinion and this place has been an excellent place to learn about diesels and related problems, so I am hoping you guys can provide some feedback as to what you might think is the problem or what I should be trying/changing.

It is difficult sometimes to trust repair shops or dealers as they try to just milk you for every penny than can squeeze from you or try and do work that doesn't need to be done, but this shop seems to be genuine in their intentions, as I opened the door for them to sell me extra parts and they told me I didn't need to change those solenoids, and they are going to install the 2 valve kits that they believe is the problem for free. Those parts are comparable in price if not a little cheaper to parts in the US if I had them shipped up here with the exchange rate and any customs and border fees, so they don't seem to be trying to gouge me in that area either.

Has anyone had similar problems with their 4l80e trani and if so, what did you need to do to fix it.

Sorry for the long post and I appreciate all the feedback.

Rob

 

[Matt Bachand]

Sounds like a genuine guy from your posts. For that cheap money I'd have them do it and see what happens.

 

[daustin]

Sounds like a genuine guy from your posts. For that cheap money I'd have them do it and see what happens.

My dually was doing the same thing a couple of years ago. I replaced the A,B solinoids and the TCC lockup solinoid. It worked fine for about 6-8 months, then pushed the front seal & bushing out by the torque converter. Needed a complete rebuild at that time. I have replaced those on a 4L60E and it is still working just fine, hit or miss with those. lol
Don

 

[Silverado6.5td]

So, I picked up the valve body for my trani today and was given some potentially good news and bad news.

The good news is the two valve kits they swapped out had play in them, which could have let enough oil to bypass causing the OD issue. They also told me the gasket that goes between the valve body and trani was deteriorated due to moisture and also a possible contributor to my shifting problem.

The bad news is that it appears the trani cooler tube in my radiator may be cracked allowing small amounts of antifreeze into the trani causing the moisture that deteriorated the gasket.

I am going to pull off the trani cooler lines and put a pressure gauge on one and an air stem on the other and pressure test ot to see if that is indeed the case. The overflow reservoir does have an oily film in it.

It was nice of them to put in 2 new valve kits clean the valve body, put new o-rings on solenoids and give me a new pan gasket for $120. He said they spent half the morning cleaning the gasket of. I know it wasn't easy as I spent over an hour cleaning off some of the gasket that was left on the trani after I removed the valve body.

Has anyone else had a problem with a cracked tube in the radiator causing fluid to leak into areas it shouldn't.

I am not sure how old the radiator is, but if the tube is cracked I need to either get a new rad or get the tube replaced in the side of the rad tank depending on how much it costs I guess.

 

[Matt Bachand]

I saw somewhere recently that there is a certain radiator you need that has a special fitting that goes in an inch or this exact same thing will happen... Let me try to find it.

 

[bk95td]

I would repair or replce the rad. before driving. A tea spoon or less of anti-freeze in the tranny will fry the clutches. Fix Now. The tranny fluid will get in the cooling system when the engine is running because there is more pressure in the tranny. When you shut the engine off the cooling system pressure is higher and anti-freeze will go into the tranny. Both systems should be flushed[tranny and cooling].

 

[midniteplowboyy]

It takes "A" and "B" solenoid for "OD", so if first gear works it should be OK, like the trans guy said. He sounds like an honest guy , most places would have told you that you needed a full rebuild.

My truck was doing the same thing, mine turned out to be the converter itself was bad.

I wouldn't worry about flushing the engine(unless you see fluid floating in the surge tank), there shouldn't be any fluid in the coolant, there is very little pressure on the cooler lines. Like bk95td said, when the truck is running and when you shut it off hot, you have radiator cap pressure pushing coolant into the trans. If you have a coolant system pressure tester, just remove the trans lines from the radiator and pressure it up over night.

Matt, your not thinking of the return fitting(rear) in the later 4L80's are you.

 

[Silverado6.5td]

I talked to a friend at my local rad shop about rebuilding the part of the rad that the trani cooler lines goes through and he said he can no longer get the kits to repair it. We are living in a disposable market now.

He said if I wanted to do an air test to check for leakage it would take a long time because the crack would be so small. He said to remove the rad and fill it will water and then pressure the coolant line an look for bubbles.

I installed the valve body back in the trani, got everything back together and took it for a drive. It still drops out of OD and throws the P1870 code, no other codes.

The 3rd and final fix specified for the 4L80E trani to fix the P1870 code is the torque converter bushing, which requires an R&R.

Not sure how much more money I want to spend on this truck.

 

[bk95td]

Have you checked the main electrical connecter for oil contamination? Tested tcc solonoid?Done a pressure test with a scan tool connected?You can command gears,pressure and tcc lock-up with the scan tool. The vave repair you had done is called sonax shure cure. The bore of the valve is drlled out and a sleeve installed creating a new bore. The tcc solonoid and pressure regulating electric valve are common failures. There also is a trans temp sensor. A scan tool will tell you what it is seeing for trans temp.
Don't condem the mechanical parts untill you are positive that the electrical is working properly.

 

[Silverado6.5td]

When you say main electrical connection, you are referring to where the internal trani wiring harness meets the external harness? The TCC solenoid tested good according to trani shop that did the valve kit repairs. I don't have the scan tool to do the pressure tests you are referring to. Which scan tool are you using to do this? Where is the trans temp sensor and the pressure regulating electric valve at on the 4l80e? Thanks

 

[bk95td]

The main connector is the big grey round one. You squeeze 2 sides to release the retainer to unplug. If there is atf inside the connector it can cause weird problems. To fix the oil seeping into the connestion you have to buy the whole internal harness.Bulkpart transmission or gm sells new internal harnesses. Or your tranny guy can get them.
A tech2 or autoinginuity software can do the tranny tests. Other scan tools may work also.
The tranny temp sensor should have brown and grey wires running to it on the internal harness. Yellow w/black stripe on the external harness.
The Pressure control solonoid[force motor] is located on the valve body. It has blue/white stripe and red w/ black stripe wires. This controls the hydraulic pressure in the tranny. If the ecm sees slippage [wrong ratio between input and output] it sets pressure to max[to save itself] making hard shifts. Take the input and output sensor out and check for gunk or fileings on the end[they are magnetic so metal sticks to them]
I have the 97 gm manual so feel free to pm me if you have more questions