85 Caprice Transmission oddities

[jase386]

I seem to be having trouble with the lockup system. Its what it feels like anyway.

When in OD its in and out of lockup on slight uphill climbs.

after everything is hot, like after 10 or 12 miles on the interstate at 70, when i get off on regular streets it acts like its staying in lock up. what im trying to describe is the transmission seems to be a speed higher than the engine can pull without lugging.

any thoughts on that?

[silicon212]

One possibility, if the clutch doesn't seem to be letting go, is the TCC solenoid. I had one of these fail on me, and that's what it does ... it lugs down until you're almost stopped, and if you don't catch it in time, it will kill the engine. It's a hassle to constantly be restarting at every light.

[jase386]

it maybe its on its way out, since sometimes the car runs and shifts fine, and other times its lugging really bad. What does TCC stand for, so i can look for one to buy, and find instructions for changing it.

what sucks is i know ill have to drop the pan, and i did that back over the summer already... hate to go thru that again, but oh well.

[silicon212]

TCC = Torque Converter Clutch. The TCC solenoid controls fluid flow to the clutch in the torque converter that locks it. It is mounted on the front pump, ahead of the valve body.

[jase386]

just drop the pan, and its up in there, toward the front of the car? ill buy one before i drop the pan, so ill knwo what im looking for, but just in general is it pretty easy to swap out?



have a valve stem seal question too, should i start a new thread? how hard is it to replace those, are they just under the valve covers?

[j cAT]

Originally Posted by jase386

just drop the pan, and its up in there, toward the front of the car? ill buy one before i drop the pan, so ill knwo what im looking for, but just in general is it pretty easy to swap out?



have a valve stem seal question too, should i start a new thread? how hard is it to replace those, are they just under the valve covers?

to replace the valve stem seals you need to use air pressure to keep the valves from falling into the bore..


you have a 305 cu gm engine this is a low cost replacement for the 350 engine once standard with this vehicle.

whats going on here is very poorly machined heads/valve guides..this causes the blue puff on start upwith a good running engine with no wear issues..

remove the heads and have the machine shop rework them to correct this ..

[jase386]

crap, i was hoping it would be something i could do from the valve covers without removing the heads. the blue puff is the only problem at all. 198,000 miles..i think, could be 298,000

i guess ill live with the puff, this thing has too many miles to go messing with too much.

(haha, dont make fun of the 305 and 307's they are gutless wonders, but you cant hardly kill either of them, and my 85 wagon gets better mileage than a new tahoe.. and im carbureted!)

[j cAT]

Originally Posted by jase386

crap, i was hoping it would be something i could do from the valve covers without removing the heads. the blue puff is the only problem at all. 198,000 miles..i think, could be 298,000

i guess ill live with the puff, this thing has too many miles to go messing with too much.

(haha, dont make fun of the 305 and 307's they are gutless wonders, but you cant hardly kill either of them, and my 85 wagon gets better mileage than a new tahoe.. and im carbureted!)

305 cu is what it is ...................

307 cu olds engine is a good higher torque engine..does not have those crappy heads and lasts a very long time if well cared for 380,ooomi is what I got ..no leaks or oil issues ..only had to replace water pump ..no engine/carb problems..

the 84 305cu however is a piece of crap..still have it ..puffed blue smoke 40,ooomiles..researched this years ago this is at that time well known to be a GM cheapo engine..under powered for the heavy caprice. gm made the bodies lighter cheaper..350cu at that time period was a very good performer..good torque so with the crappy tranny it would shift better..700r4........another cheapo componet..

sorry I got carried away with this b/s......

[jase386]

still amazes me that a cheapo from 85 will still last longer than some of the good stuff they are putting out today. and just as good fuel economy.

anyway, back to the transmission. went for a drive and the problem is its wanting to stay in lock up. so im thinking tcc solenoid, but when i tap the brake, no matter what gear im in, it comes out of lock up like its supposed to, then soon as i release the brake pedal, back to lock up. is that the solenoid going bad, or is something else telling the ECM it needs to be in lock up?

[GirchyGirchy]

What speed are you going when it locks back up? If it's a decent speed, then I'd think this is normal. Mine's always done this, so if I don't want it to bog down, I'll just give it some gas to make it unlock or downshift.

Heck, mine's started locking out in 3rd after having the carb rebuilt and TV cable adjusted.

Speaking of valve guides, I think mine has that issue as well. I've read that problem can cause pinging as well and mine's always done that.

[jase386]

after driving for a while in lock up, say on the interstate, then it doesnt want to come out. After it goes in, and i stop and take off again, its allready locked when i shift into 2nd gear at 10-15 mph which is too slow to be in lock up. shouldnt do that until youre in OD and running steady speed.



thing is, even in 2nd gear, when i tap the brake it comes out of lock up and goes back in the second i release the brake. so the system is working correctly in telling it to come out, im just wondering if there could be something else trying to make it stay in lock up? im going to replace the solenoid when i get time, its just too damn cold right now to be laying under the car messing with that pan.

[j cAT]

Originally Posted by jase386

still amazes me that a cheapo from 85 will still last longer than some of the good stuff they are putting out today. and just as good fuel economy.

anyway, back to the transmission. went for a drive and the problem is its wanting to stay in lock up. so im thinking tcc solenoid, but when i tap the brake, no matter what gear im in, it comes out of lock up like its supposed to, then soon as i release the brake pedal, back to lock up. is that the solenoid going bad, or is something else telling the ECM it needs to be in lock up?

many things will effect the shifting ...poor engine performance is a big one ..your engine has about 1/2 mile of vacuum lines..did you check with a vac guage for leaks ? how old are these hoses 26 yrs ?

any hose with cracks is junk !

when did you replace the tranny filter ? what fluid did you use ? dexron III is no longer licensed by GM ..use of the dexron VI is recommended..

fluid level must be correct when hot too much or too little will effect shifting..

products are available to clean up the transmission system..

with dexron III I have used transmedic ..this helps loosen deposits ..then do the fluid replacement /filter of the transmission..

with a vehicle this old replacing the tranny fluid 3X would be a good idea,,

[silicon212]

Originally Posted by j cAT

many things will effect the shifting ...poor engine performance is a big one ..your engine has about 1/2 mile of vacuum lines.. /content deleted for brevity/

Dude WHERE DO YOU GET YOUR INFO FROM?

I'm sorry but I see so much damn misinformation in this thread it's pathetic! A half-mile of vacuum line? A half mile in HO scale perhaps? Not even that much! I'd be surprised if there are more than 30 feet of vacuum line on the entire car, air conditioning included, and that includes hard line and the steel purge line to the fuel tank!

Dex III in a TH700R4/TH350C is just fine, no need to get him into synthetics for this transmission! So, it's no longer 'licensed'. That doesn't turn the chemistry into junk all of a sudden.

Likewise, a dirty filter won't make the lockup screw up, but it could make the transmission slip.

jase386 - take this from an intuitive thinker - my diagnosis of the TCC solenoid is likely into the 90th percentile. Sure, there could be other problems but the two major ones are a bad torque converter (10% and that's likely liberal), or a faulty TCC solenoid (90% and that's being conservative). One possibility is the brake pedal switch if it's not disengaging during braking - but in that instance, it'd still otherwise work normally.

[silicon212]

Originally Posted by jase386

just drop the pan, and its up in there, toward the front of the car? ill buy one before i drop the pan, so ill knwo what im looking for, but just in general is it pretty easy to swap out?



have a valve stem seal question too, should i start a new thread? how hard is it to replace those, are they just under the valve covers?

OK, it's not difficult to swap out. There are two or three pressure switches that the wiring harness to the TCC solenoid connects to, depending on the year. They make "universal" solenoids that work on both the 700R4 and 2004R, but these require cutting and splicing in line with the harness inside the transmission. Always the better option, get the original one for that transmission, complete with the full harness.

As for the valve guide seals, these are best replaced with the cylinder heads removed from the engine. If all you're seeing is a puff of smoke when you're starting up, then I wouldn't worry about it. The seals get hard and brittle after so long in the engine, being made of Neoprene and whatnot. You might notice that your oil consumption, between oil changes, will increase by about half the amount of one of those 100 calorie Coke cans (4 oz). That's 8 tablespoons.

Don't listen to others as to what 'junk' a 305 is, and don't listen to those tell you it's 'cheap', either. The only difference between a 305 and a 350, including in quality, is about .25" of bore. The 305 was intended as an economy engine, not as a cheap engine. It's a good, reliable engine that lasts forever when properly cared for and treated, like any other small block.

[jase386]

Silicon,

Earlier in the thread or in the other thread you mentioned the TCC thats why i began paying attention to when or if it was going into lock up.

Thats when i realized that its wanting to stay in lock up all the time, however when i brake, in any gear, it comes out of lock up only to lock up again as soon as im off the brake pedal.

i wanted to make sure thats a sign of a bad solenoid and not some sensor somewhere else telling the ECM it should be in lock up no matter what speed im going.

i just hate to drop that aggravating pan if the solenoid operation is a symptom of some other process instead of the root of the problem.