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In gear but slow to move...

E

EdPDX

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Portland, OR
My army Blazer runs and starts fine but now with the cooler weather I am noticing the transmission (I think) is slipping when I first start it in the morning (Or whenever it sits a few hours).

I warm the engine a couple of minutes and shift through all gears (Auto trans). The vehicle does not move in gear either direction. I slowly give it a little gas and in a few seconds I can get it rolling. Once I'm under way it get progressively better each time I stop at a light or sign.

When the transmission has been working for about 5 minutes it runs as it should- there is a hint of slipping- then it catches and runs well.

I am new to diesel so I am wondering if this is due to low IP pump pressure- changed to a new green line Fram modulator- no help. Is this a possible IP issue? A VRV Issue... or is it strictly a slipping transmission issue? :dunno:
 
sounds like a slipping transmission. Go grab some Lucas trans fix and see if it helps.
 
So the lack of vacuum or pressure from the IP could NOT be the cause of this apparent slipping?
 
EdPDX said:
So the lack of vacuum or pressure from the IP could NOT be the cause of this apparent slipping?
Click to expand...

Well I am learning all this diesel stuff now, but a transmission like a 400 is not vacuum operated except to shift into 3rd.

First and reverse are both total fluid engagement. So vacuum would not have an affect on these at all.

At this point whatever you do, do not flush your transmission sure way to kill one that is going out.

Did you pull the dipstick and smell the fluid? What is the color? Does it smell burnt?
 
Its a TH400 trans.

First warm up the truck, and check your trans fluid. You can be low, check the simple stuff first.
 
The transmission fluid is as pretty pinl/purple as you could ask for. It is not burnt.
Question: So the vacuum/pressure at the modulator does not actually shift the transmission?

I already put new rubber in all the way to the modulator. I found that the vac line that runs from the VRV to the back of the engine (the lower one) had a reducer in it. It cuts the vacuum way down to the VRV. My truck was already warm so I don't know it it made a diff taking the reducer out of the vac line. I'll see in the morning. I thought maybe the low vacuum affected the modulator and made it hard for the transmission to get in gear.

Can the IP be checked to see if it is bad? I have a new VRV I have not tried yet. The glass check ball is clear in the one that is installed now; but I don't know it the valve is bad or not, or is the IP is bad or not.

I wanted to rule the vacuum out before taking the blazer to the transmission guy and having him rebuild it.
 
Not engaging a gear, whether forward or reverse, when cold has nothing to do with vacuum, or your IP or what color the seats are. You still haven't answered whether or not you have checked fluid level as per the instructions on the dipstick. Usually when at operating temps, and in park. If the fluid is pink and the truck is new to you it may just have been changed prior to the sale to mask a tranny problem. If you've had it a while and it's pink it's probably just a couple of qts low. It's not uncommon to lose the seal between the tranny and T-case...so you don't see any tranny fluid on the ground, but you are losing it steadily into the T-case.

Pull the inspection plug from the T-case while on level ground...if tranny fluid comes pouring out your seal is gone.

If the seal isn't a problem, and the fluid isn't low...take it to a tranny shop.

Rene
 
I changed the filter and topped it of again with fluids after I bought it. I did not flush it. The fluid level is not low in the least.

I have a 73 C20 that was slipping a few years ago. I took it in and ended up getting a new transmission- not too bad $400 and change. I will take this in after doing as you recommend- where is the the inspection plug on the transfer case?

And am I correct to have the shop rebuild the existing transmission? Any tips on what to ask for or avoid at the transmission shop?
 
If you look at the backside of the T-case you'll see two big hex head bolts...1" wrench or near to that. There is an upper one and a lower one. Remove the upper one...no fluid should come out. The correct fill level is fluid to the bottom of that hole. The lower one is the drain...

No reason not to have that tranny rebuilt as long as the case itself is good. It doesn't sound like there is "hard part" damage. You can check that yourself too though...just drop the pan on the tranny and see what's in the bottom. That'll help reduce the bullsh!t when you do take it in.

Rene
 
manybe fixed

:woot:I dropped the pan today. The plastic tube that runs from the filter to the transmission was a little sloppy. I changed the gasket and filter and bought two slightly larger O rings- put them both on and could feel a serious seal when the tube went into place.

Refilled the oil to the mark with type-F fluid. Was not up to figuring out how to drain the converter so I may have to make a few more drain and fillls to get the proportion heavier on the type-F.

The M1009 was fired up and as soon as I put her in gear she started off down the road.

Hope it lasts.

thanks for all the suggestions
 
EdPDX said:
:woot:I dropped the pan today. The plastic tube that runs from the filter to the transmission was a little sloppy. I changed the gasket and filter and bought two slightly larger O rings- put them both on and could feel a serious seal when the tube went into place.

Refilled the oil to the mark with type-F fluid. Was not up to figuring out how to drain the converter so I may have to make a few more drain and fillls to get the proportion heavier on the type-F.

The M1009 was fired up and as soon as I put her in gear she started off down the road.

Hope it lasts.

thanks for all the suggestions
Click to expand...

May I ask why you are using type F?
You are supposed to use Mercon III with friction modifiers, type F doesn't have those and you will have a Harch shift, unless you are doing that for that reason to feel like you have a shift kit, I wouldn't use it.
 
imiceman44 said:
May I ask why you are using type F?
You are supposed to use Mercon III with friction modifiers, type F doesn't have those and you will have a Harch shift, unless you are doing that for that reason to feel like you have a shift kit, I wouldn't use it.
Click to expand...

That's the same question I had. Why would you use a different fluid than what's specified?
 
Well I have had it running since the work on the filter and topping back up with Type-F. I know that this is not the spec'd fluid; but the Dex/Merc that was in it was slipping so bad I could scarcely get moving when it was first cold. Now I put it in gear, the shifting is about where all my other Chevy's are. Just a hint of a bump to let you know the gears have engaged. And off I go. There is no more slipping in third as I travel grades with small loads.

The pan was emptied; but not even half the transmission fluid came out. I did not drain the TC. So there seems to be a blend that is working so far- the shifts are not harsh, so this is working for me until the spring. ... now for the Heater Core :whistle:
 
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