Gearbox Problems

[kingtom]

Hi all

Hoping that there is Auto box Guru that maybe able to help.

Just fitted the Nomad valve body kit from wholesale automatics on the 80 series 12 valve and on first test seemed to be working great. Smoother through the gears and even making the truck feel like it has a lot more power.

Problem is on a long run once the box has got to temp around the 80-90 degree mark and in top gear 4th. If i start coming down hill and ease off the accelerator the temp rockets straight up to 140. I obviously pull over to let cool but if I leave it in Park it still creeps up and I have to turn the truck off.

I have had the ATF replaced for Dexron 3 and the levels look good, transmission cooler looks good ie not clogged.

Any help would be much appreciated.

Cheers

Tom

 

[Jon Wildsmith]

I would give wholesale a call or email, they are usually very helpful and are more likely to know what's wrong. I'd guess either the valve body is faulty or one of those pesky little centre support gaskets isn't sitting right and that's interfering with the valve body operation.

 

[kingtom]

Thanks. I have emailed. Just hoping they are not shut for christmas

 

[Jon Wildsmith]

They are strange symptoms that's for sure. I think you will be removing the new valve body whatever the diagnosis. If the old one is intact I'd refit that and prove / disprove the problem is the new valve body and at the same time be able to check that it's not an installation issue e.g. those centre support gaskets which can be a bugger to get to stay put while you fit the valve body.

 

[kingtom]

Yes its very strange had a bit more of a mess around with it today and it works fine and keeps good temp and then after about 30mins it all goes wrong. Any downhill where you take your foot off the gas, the temp shoots up and from then on it all goes to pot.
Ive now disconnected the nomad lock up ecu thinking it might be electrical but the symptoms are the same.

Bloody annoying

 

[Jon Wildsmith]

I can imagine, I've played swap the valve body a few times myself in the past

 

[kingtom]

Well just spoke to wholesale transmitions and they have no idea why i am getting these symptoms. "Doesnt make sence" there words exactly.

Back to the drawing board

 

[Jon Wildsmith]

Did they have any advice?

I think because the symptoms are quite strange it would be important to rule out other things that seem unlikely but under the circumstances are worth checking. E.g. is it really getting hot and not just a sensor problem? Is it the box making the heat, or is it the engine and the heat is being dumped into the box and cooler making it look like a box problem?

Do you have an extra oil cooler or just the OEM in radiator one?

Do you have an engine coolant temperature gauge apart from the OEM one?

You may have already done this but I think I'd confirm it really is getting hot so check the oil pan is close to the temp when getting hot and also check the oil cooler pipes at the radiator, or of you have an extra cooler check that. Your symptoms suggest the oil cooler will be relatively cool when the box is getting hot i.e. no or very little fluid flow through it but the pan should still be near to indicated fluid temp. If the lines and cooler are clear then really that would implicate the valve body which is in charge of sending fluid to the cooler. iirc when the TC is locked there is no fluid flow through the cooler because the TC lockup is in the same circuit and blocks the flow but that's ok because the box shouldn't be making heat with the TC locked. I'm wondering if the valve that controls that is sticking, not enough to keep the TC locked but enough to severely restrict flow to the cooler. But stationary in P the temp shouldn't still be rising or not for long, that really doesn't make sense because the box shouldn't be generating much heat, unless the TC lockup still has some pressure applied and is dragging ...

 

[kingtom]

Hi Jon

Yeah this is very peculiar. When speaking to Wholesale Autos they said there is no way it should be doing that. I even mentioned a sticky lock up valve and again they said that wouldn't affect it and also said they didn't believe its the valve body or oil cooler

One thing that I didn't at first think would affect anything, was when I removed the original temp sensor from its housing the plug snapped off. I bodged it together again and thought nothing of it. I am now thinking that there may be a short which is now affecting the gauge as its sensor is next to it. I have unplugged it and still getting the same problem though maybe not so pronounced (hard to tell), so maybe there still could be a small short to the casing which the new gauge sensor is picking up? (Stab in the dark)

Anyway I am not convinced it is getting that hot. When it was reading 140 I have been underneath to feel and its hot but I wouldn't say 140 degree hot. Wholesale suggested getting an inferred heat gun. Obviously I don't have one so going to get some stick on heat sensor strips that should tell me the hottest it gets. Though all I can find is 120 degree ones.

 

[Jon Wildsmith]

Normal running temp is probably 80-90 degrees, 120 would be working very hard kind of temp, so if you use a 120 strip and it goes off the scale I think you can say it is getting very hot but if it's a sensor problem and not really getting that hot then should be well within the 120 scale. 140 is very hot, lots of radiated heat from the oil pan. An IR heat gun is a useful thing to have for measuring all sorts of things and not all that expensive I don't think, would be more accurate.

 

[Andy]

Tom,
just checked on Maplins website, they do an infrared thermometer for £19.99, that will do the job, take jons advice & get one!
You can also check the flow & return temps with it too

Andy

 

[kingtom]

Cheers Andy. 3 in my local shop down the road. picking up tomorrow

 

[kingtom]

Taken over the kitchen table. Missis is going ballistic

 

[stumog]

Would be a great picture if showing.

 

[kingtom]

Trying again

 

[Ian Chuter]

Ooooh yeah, I can see she could get a little arsey about that ..........especially around tea time Good luck with that!

 

[clivehorridge]

Ooooh yeah, I can see she could get a little arsey about that ..........especially around tea time Good luck with that!

At least there's a cloth on the table, should stop (some of the) spillage

 

[kingtom]

yeah my bad thats the very special Christmas table cloth. oops

 

[Chas]

At least there's a cloth on the table, should stop (some of the) spillage

Yes, I noticed that, very thoughtful of kingtom, I can't see why his missus should complain.

 

[stumog]

Bet she is going to love you doing that.