CUCV 1986 M1008 - In a Real Pickle - Bad Heads - Need Advice

[Tinstar]

ACDelco 60G's are what you want.
They are self regulating.

Most guys use the 60Gs with zero issues.
Me included and over two years without a single issue.

A few still use the 13Gs.

Your call

 

[cucvrus]

13 G is what came from the factory. I have the GM part number if you want it. The 13 g is a 3/16" tab. The others have a 1/4" tab. My choice is to retain the 13 G I also retain the ballast resistors on the firewall. I don't have a problem if you don't. But if you want the GM PN for the AcC Delco 13 G glow plugs I will post it just say. I am sitting outside at a party and want to remain here for now. Take care and report back. i will follow up if you want the number.

 

[Commander5993]

Hummm.... what happened to the last update I posted a few weeks ago...?

Well, what I thought I posted before, was that the new GP's worked! No More Smoke!
The Truck has been running good, the only other issue I had was the new temp sensor for the idiot light died after less than 2 weeks... which caused the idiot light to come on even though there was nothing wrong, and the truck wasn't hot at all. The new temp gauge I installed when I redone the heads, showed it was only around 170 to 180 degrees. I even pulled the rad cap off, and it was fine, not boiling, steam, or anything.

So I bought a new temp sensor, this time from oreilies, and installed it, and the temp light has stayed off ever since.


Now for the bad news....

although the engine has been running good... it now seems I have an problem with the transmission.
I have noticed several times in the last 2 weeks, that when going down the road, when the gas pedal is pressed, the engine would rev up higher than sounded normal... but the truck didn't seem to be picking up speed...
But then, you might let off the pedal and hit it again, and it seemed ok. It doesn't seem to do this when you first hit it from a dead stop, but rather after you are already doing like 20mph or so, and you try to speed up further.
As I said it has done this several times.

I have checked the fluid several times, it was in the "safe" zone, down maybe half a pint. It isn't burnt... but it isn't as "pink" as new fluid would be.
I did add some lucas transmission fix to it, but only up to the fluid level full mark.

We drained and replaced the fluid and filter back about 5 years ago.

I ordered a new filter kit a few days ago, and thought about changing the fluid and filter... but will it do any good?? Am I just wasting my time and money?
Does this... "slipping"... show that the transmission needs rebuilt?
Could there be some other issue that could cause these kinds of symptoms?

If it needs rebuilt, how hard is it to do? I've seen a lot of people online who claim to have rebuilt a TH-400 on their own. Apparently it is a "simple" transmission compared to many.
Is there a place that a good quality rebuilt transmission can be had for a reasonable price?

As Always, All Input is Appreciated!

 

[cucvrus]

We drained and replaced the fluid and filter back about 5 years ago.

That my friend is quite the long service interval. I doubt that is helping matters. I would still change it and service the filter. I try and change mine and service the filter every 2 years regardless of mileage. Good Luck. I let transmission rebuilding to a professional. I can rebuild the engine easy enough. But other parts are not as easy as others lead on it is. a lot of stuff going on in the TH400. But what do I know. I am just a poor dirt farmer here in Jonestown PA. Have a great day. Keep your belts tight and your fuel tank topped off.

 

[Commander5993]

We drained and replaced the fluid and filter back about 5 years ago.

That my friend is quite the long service interval. I doubt that is helping matters. I would still change it and service the filter. I try and change mine and service the filter every 2 years regardless of mileage. Good Luck.

hummm..... should've read that manual closer... guess I'm used to newer vehicles which have longer service changes on the trans fluid. And yeah, I guess I was mostly thinking about the milage too. I'm usually pretty good about keeping up with stuff like that, most of the time even changing fluids before its required... but failed this time.

Changing the fluid at this point probably just make it worse, right? As right now all the debris in the fluid may be whats giving it traction.

I let transmission rebuilding to a professional. I can rebuild the engine easy enough. But other parts are not as easy as others lead on it is. a lot of stuff going on in the TH400.

Yeah... kind of what I was thinking to. Some make it look easy enough, but a lot of parts in there... just needs one peice to be wrong...
I may look into a local shop here... i think there is at least one place that rebuilds transmission here.

But what do I know. I am just a poor dirt farmer here in Jonestown PA. Have a great day.

You know a Lot when it comes to CUCV's

Keep your belts tight and your fuel tank topped off.

Copy That.

 

[cucvrus]

I say no to doing more harm then good. Change the fluid and filter. The shift could just be the modulator on the right side of the transmission. And that cost me $40. at a local shop to have diagnosed and changed. I trust this guy. I had one of my M1009's shifting horrible and dropped it off think the worst. He called me an hour later and said hey your trucks fixed. I said how. He said the vacuum lines were on upside down in the rubber guide at the valve on the injection pump. HMMM how did that happen? Well I don't know but it did. I do remember having the air cleaner off and cleaning up under the hood. The rubber block was cracked and I messed with it and changed it. That easy. $20. When's the last time you took a truck to the shop and got a $20. bill? Lifetime of living in the same area and not being a BS guy. Keep your friends close and your enemies closer. Have a great day. Looks like we will have a great weekend coming up. Take care. good Luck. Report back. Get a transmission pan with a drain port. Or NOT.

 

[Commander5993]

I say no to doing more harm then good. Change the fluid and filter. The shift could just be the modulator on the right side of the transmission. And that cost me $40. at a local shop to have diagnosed and changed. I trust this guy. I had one of my M1009's shifting horrible and dropped it off think the worst. He called me an hour later and said hey your trucks fixed. I said how. He said the vacuum lines were on upside down in the rubber guide at the valve on the injection pump. HMMM how did that happen? Well I don't know but it did. I do remember having the air cleaner off and cleaning up under the hood. The rubber block was cracked and I messed with it and changed it. That easy. $20. When's the last time you took a truck to the shop and got a $20. bill? Lifetime of living in the same area and not being a BS guy. Keep your friends close and your enemies closer. Have a great day. Looks like we will have a great weekend coming up. Take care. good Luck. Report back. Get a transmission pan with a drain port. Or NOT.

You can't even hardly get a bill for less than $20 if two people go to a fast food restaurant anymore... let alone a truck service bill.

Anyway, I'll drop the pan, look it over, see if I can see any seen any metal shavings or anything. Change the filter and fluid... which only changes out about what 40% of the fluid? Would have to have it flushed to change it all, which wouldn't be a bad idea really. Might call that place and see what they would charge... wish I had a shop around here I could trust... thats why I've always done everything I can myself, as every time I have taken something to a shop, it seems like I always got screwed over, no matter where we have lived, either by 2-3 times the money it should have been, or by a crap job which i usually don't find out until later.

Does the CUCV standard trans pan not have a drain port? This one does... wonder if that means it was already changed out with an old civy junkyard find by someone.

I did just connect all the vacuum lines when I redid the heads. As None of the lines were even there, the pump was "capped" off, and nothing was connected the IP nor transmission vac hard lines.

I wonder if either the... module?... on the IP is bad?
Or if the modulator on the transmission is bad? It would be worth replacing just to find out, as if one of those is the issue, then thats a whole lot cheaper than having the transmission rebuilt... I think I hooked the lines up right... guess I could switch them just to see what happens

Yeah looks like it going to be fairly nice for the next few days, still be warm at least, they are giving us some showers but thats ok.
Got to enjoy it while we can.... I've been looking for it be a bad winter this year for a while now. Got to finish getting my firewood split and stacked... wanted to have it all done back in the summer, but just one thing after another, never got around to getting it finished.

Thanks Again & Have a Good One

 

[cucvrus]

You need to make sure of a few things. Do you have good vacuum? Are the rubber hoses sealing on the module at the injection pump? Is the module adjusted properly? And is the signal reaching the modulator thru the vacuum. get it set up properly and change the filter and fluid. It could be hanging in gear because it is being poorly signal to shift at the correct time. And is the down shift wire/switch functioning properly? Let it up to a professional if you are not qualified. Missouri is out of my range for recommendations. Good Luck. Take care and report back.

 

[Commander5993]

Ok, well, dropped the transmission pan today. And you were right, no drain plug.
I could have sworn that I had seen one on it before...

Anyway, pan was clean. There was a "doughnut" magnet about 2 1/2" across in the bottom of the pan. It had a layer of "sludge" on it, which felt smooth when rubbing it between your fingers. So at least not a bunch of bigger metal shavings or anything.

Removed the filter, it also looked ok... not that you can tell how dirty (or not) it is inside.
Valve body and everything else in the bottom of the transmission looked perfect and was clean.

Fluid wasn't bad, no burnt smell or anything. When you wiped it off on a white paper towel, it was a little brownish and darker, but was still red. Just not near as "pink" when compared to new fluid on a white paper towel.

While the pan was off, I did notice what I originally thought was a temp sensor or something that has been disconnected all this time, that inside the transmission there is a wire that goes over to what looks like an electromagnet, some type of solenoid. Would this be the "downshift switch" you mentioned?? I had seen the blade connection on the outside of the transmission before, but there is no wire anywhere to connect to it. When I thought it was just a temp sensor, I wasn't too worried about it. But if this is the downshift switch, then I guess I'm going to have to figure out where its supposed to connect and run a whole new wire.

Anyway, Cleaned up the pan, and magnet, put the magnet back in the pan. Only had to clean off one or two small spots on the bottom of the transmission where the old gasket stuck.

The new gasket was of course folded up into a "ball" in the filter kit box, and didn't want to cooperate. So I used some of the "right stuff" gasket maker to lay a bead all the way around the pan, then used that to hold the gasket in place. Went ahead and put another bead of "right stuff" on top of the gasket while I was at it, just to make sure it got a good seal on the transmission.

Reinstalled the filter and pan. Then let it sit for about... half hour or so, just to give the "right stuff" some time to set up a bit.
Refilled the transmission with dexron VI back to the full mark. Took exactly 6 quarts.

Took it for a test drive, engine was still revving high before it would shift from 1st into 2nd.
So I took the transmission vacuum line a loose from the IP module, no change. Still revving high.

So, just as a test, I connected the vacuum pump line directly to the transmission hard vacuum line. At that point, the truck would shift from 1st to 3rd (I think) at around 15mph. And it was so soft of a shift, you could barely even notice it. I think it was shifting directly into 3rd gear, because it only would shift once, so I think it was skipping 2nd gear at this point.

From this "test" I can only figure that it is the vacuum module on the IP that is bad.
So I'm going to search to find the part number for that, and try to get one ordered.

I REALLY hope that this is my only problem, and that the transmission itself is fine. Certainly don't have the money right now for another transmission.
Especially right after replacing the heads and everything else...

 

[ken]

The valve on the IP might be out of adjustment. You can lossen the two bolts holding it on and rotate it forward tward the front bumper or backward tward the cab to adjust shift points. Rotate forward tward the front bumper to shift sooner. Try adjusting it before you buy a new one.

 

[Commander5993]

The valve on the IP might be out of adjustment. You can lossen the two bolts holding it on and rotate it forward tward the front bumper or backward tward the cab to adjust shift points. Rotate forward tward the front bumper to shift sooner. Try adjusting it before you buy a new one.

Yeah, I was going to try that too. Hadn't found what you had to do to adjust it, but was going to search about it. Thanks Ken for the info.
I'll try that tomorrow. None of these lines, the vac pump, or either module was hooked up before, so who knows.
If that doesn't work, then I found a new AC delco one on ebay P/N 14057219 for $32. Its $100 on amazon...

 

[german m1008]

.........why do you use dex VI if you can read it everywhere.....dexII or dexIII.....
I do not want to give the wiseguy here, do as you wish,
Maybe there is a reason why dex II/III is required and not dex xy.
Maybe you open another can of worms, maybe some additives are not the best for your old th400?
Again, do as you wish, no offense, ........ sometimes it could be so simple

 

[ken]

Dex VI is a thinner vis than IV. This could make your torque converter slip a little more. More so if the truck is loaded or towing something. This could result in higher tranny temps, worse fuel mileage and shorter tranny life. Oh and I was backward thinking on the vac valve adjustment. rotating forward results in shifting later "higher RPM". There are two screws holding it on the passenger side of the IP. These screws are in slots. So you can loosen them with out taking them off. Then rotate the valve forward or backward to get your shift points where you like them. Udjust the valve then test drive it to see if it's where you like it. You will want to do this with the tranny warm. Mine shifts at a higher RPM until the truck warms up. Then shifts pretty normal. Also do your test drives on flat ground for better consistency. You can also take the valve off the truck and test it by blowing through one of the tubes. Just turn the orange valve by hand while blowing through the tube. You should feel the restance change as you turn the valve. And or feel any leaks while blowing.

 

[Commander5993]

.........why do you use dex VI if you can read it everywhere.....dexII or dexIII.....
I do not want to give the wiseguy here, do as you wish,
Maybe there is a reason why dex II/III is required and not dex xy.
Maybe you open another can of worms, maybe some additives are not the best for your old th400?
Again, do as you wish, no offense, ........ sometimes it could be so simple

There's a bunch of guys on here who use dexron VI without any issues.
It is supposed to be fully compatible with dex III applications. Its also a fully synthetic fluid as well, so it shouldn't break down as quickly.
And I already had a case of it here.

 

[Commander5993]

Dex VI is a thinner vis than IV. This could make your torque converter slip a little more. More so if the truck is loaded or towing something. This could result in higher tranny temps, worse fuel mileage and shorter tranny life. Oh and I was backward thinking on the vac valve adjustment. rotating forward results in shifting later "higher RPM". There are two screws holding it on the passenger side of the IP. These screws are in slots. So you can loosen them with out taking them off. Then rotate the valve forward or backward to get your shift points where you like them. Udjust the valve then test drive it to see if it's where you like it. You will want to do this with the tranny warm. Mine shifts at a higher RPM until the truck warms up. Then shifts pretty normal. Also do your test drives on flat ground for better consistency. You can also take the valve off the truck and test it by blowing through one of the tubes. Just turn the orange valve by hand while blowing through the tube. You should feel the restance change as you turn the valve. And or feel any leaks while blowing.

Dexron VI does have a little lower viscosity, but from what others here have said it should actually increase fuel milage... if it's enough of an increase to actually be noticeable I kind of doubt it personally.
As I said in my last post, there are multiple guys here on SS who have been using dexron VI without an issue. I think it'll be fine.

I did try to adjust the vacuum module on the IP... at first it did nothing at all... then just for the heck of it I switched the vacuum lines as I had tried to see in the TM's about which one was supposed to connect to which place on the IP module. But couldn't really find anything that showed. I then tried to find photos of it, but was only able to find a couple on google where I could kind of make out the lines. After switching the lines, I rotated the module to fully back toward the cab (as it was nearly that far back anyway), and at that point you couldn't even hardly feel it shift. But at least I knew it was working. So I guess I had the lines backwards.

The adjustment on it is Really touchy, as in I can move it about 1/4" or so, and it will go from seemingly like there is no vacuum connected at all, to so soft of a shift that you would think it is full vacuum directly connected from the pump.
After adjusting it about 5 more times, doing test runs in between, I think it's in a decent spot. I'm going to leave it where it is for now, and will see when we drive to town next time. Might adjust it slightly from there.

Thanks Once Again for all Info and Help All!

Will update later this or next week, once I've had a chance to see if all of this has fixed the issue.

 

[german m1008]

There's a bunch of guys on here who use dexron VI without any issues.
It is supposed to be fully compatible with dex III applications. Its also a fully synthetic fluid as well, so it shouldn't break down as quickly.
And I already had a case of it here.

The TH400 wasn‘t designed for Full synthetic oil, just because it works for a while will not be more correct.
I wish you and the others good luck......
Even at the risk that I'm just not more popular........I‘m far far away from being an expert but I am convinced of one thing, the most issues people have with their cars or trucks are caused by no or wrong maintainance, using bad quality or wrong parts for their repairs or using wrong engine oil, coolant, atf or whatever or experimenting and being innovative.
What do you mean, how long will a 6.2 diesel last with 0W30 ( full synthetic) wich requires 15W40 HD ( mineral)?
That‘s only my opinion.......
......and at the end of these experiments, when they are unsuccessful is mostly written.....GM can not build good cars.
At the end everyone makes what he believes in......like the man in this old joke
„a man runs loudly screaming through Munich,
another man asks him why he cries all the time.....and the man says, so the lions disappear.......
whereupon the other replied that there are no lions.........and the screaming one says.....you see, it works.
...... really not meant evil

 

[Commander5993]

thought I would post a little update... or the final update as it were...

Truck had been running fine... got all the little "kinks" with the vacuum lines, and other little things sorted out.
Got the backup camera and some other little things fixed inside the cab as well.

have been driving it for... about a month and half I guess since I installed the new heads.

Today my mom wanted to go up to the little town only about 8 miles from us to pick up a few things.
About half way there, doing about 45mph, with no warning at all there was a loud "thump" and the engine died instantly. On a country road, pulled off to the edge in the grass. Popped the hood, looked it over, didn't see anything wrong, no leaks, no broken belts, nothing.

With it in park park, tried to re-start. Crank and crank, but nothing, didn't even try to hit or anything.
So my dad and I used another family members truck to tow it back home.
Got it here, looked the engine over more, still nothing. Tried to crank again, nothing. Sounded like it just wasn't getting fuel, however I know from the way the engine died instantly that was very unlikely to be the issue.

Just for kicks, opened the vent on the fuel filter, cranked the engine, plenty of fuel pumped out the vent line.

Got some starting fluid out of the garage (yeah I know its bad, but at this point I figured it wasn't going to matter), let my dad spray just a shot into the air filter while I was cranking the engine.
It tried to hit. So, without adding any more starting fluid, I cranked it again, it hit several times and this time we could defiantly hear something internal that did not sound good at all. Hard to describe, sort of like several hard knocks and grinding... sort of...

Anyway, what ever is broke I'm guessing is some main internal part(s). I'm figuring the crank broke personally, but could be the cam...? I don't really think it was a piston rod, just didn't sound right.
In any case, this truck is going to be sitting for a while... or we may just sell it, although I hate to as we have about $12000 in it. Don't have the money to rebuild the engine, and at this point I don't even want to. If I would do anything, I'd put a new engine in it, but don't have the money for that either.

Looks like we're going to have to sell our deuce and a cargo trailer to buy another vehicle, as all we have at this point is the old dodge truck we're borrowing.

 

[dependable]

Sorry to hear that. Suggest you remove timing cover and see what moves, or does not, when you crank.

 

[Recovry4x4]

That stinks. Hope a nice inexpensive 6.2 falls from the sky.

 

[Drock]

Sense your invested $$$$ at this point I'd pull all the glow plugs and do a compression check before jumping to conclusions. That will tell you everything you need to know.