Mosephus

Hi,

I recently bought a 98.5 and I'm starting to have a few problems, over the last month the idle has been falling more and more it has fallen from 800+ to around 550 to 650 and the truck is dieing alot. I know where to adjust the idle but the idle progressively getting lower is weird to me. Along with this problem the transmission has been getting very hot around town, on the highway it'll hold around 180* but around town the trans got up to 240-250 yesterday and started slipping (not good), The trans cooler was VERY hot, (enough to burn off the water I sprayed on it). This could be because I'm having to power brake the truck at lights lately to keep it from dieing. The previous owner claims the trans has been built with all the goodies.

Sorry for rambling on. Anywho, what could be going on? Here is a list of things that have been done to it.

It has a 100 plate and a 3k GSK timing is set at 16.5. 5" exhaust to 6" miter cuts and a built trans with a slightly higher stall converter.

Any ideas? I'm sorry if this doesn't make much sense, this is my first Diesel.

torquefan

Hi.

Sounds like your truck is a 98.0 (12 valve), and not a 98.5 (24 valve) right? It's pretty common for the idle to drop off on these trucks periodically. The idle screw is hidden towards the rear of the injection pump, and the head of it will wear from the throttle lever riding against it. It just needs to be turned to a fresh spot, and in extreme cases, you may need to smooth it out with a piece of sandpaper.

Not real sure about your transmission, other than making sure the cooler fins aren't restricted and none of the lines are pinched. If it slips, it will generate heat fast. Maybe it is slipping more than you are noticing?

brockdieseldude

That temp is WAY too high, I hope that clutch packs are not warped but thats close to burning up the trans.. How hard are you power braking it to keep it running?? I wouldn't think anything under 800 rpm should super heat the fluid even with a super low stall. I would wonder if the check ball in the cooler line is sticking not allowing good flow to the cooler. I would recommend getting that truck to a good trans shop and having that issue checked before it cost you a trans... As far as the idle issue thats not hard to fix its kinda hard to see but it takes a 10mm wrench to get the jam nut loose and then you can turn the idle screw with you fingers from the bottom most of the time. The screw is near the bottom rear of the pump, thats not a real good description I know but thats about the best I can tell ya. Good luck man!!! I hope this helped a little.

Mosephus

Sorry yes it is a 98, is 180 too hot for these trans too? Also should you adjust the idle with the engine running?

When I say power braked I meant I'd just hold the idle at about 900 rpms while sitting there, most of the time I just throw it in neutral when I have to come to a longer stop. The cooler could be clogged, when I got home after the trans got that hot I opened the hood while it idled and hosed the cooler off, I also grabbed the upper line and it was too hot to touch, but the lower line coming out of it was not hot at all really. I suppose the cooler could be clogged.

brockdieseldude

No 180 is fine 210 is getting hot. You can adjust the idle with it running it is easier that starting and stoping the engine a bunch of times to get it right. it sound to me that the cooler line or cooler itself is clogged up somewhere, because both those lines should be hot. I would check your fluid for color and smell to see if its burnt, you may need to go get it serviced after getting it that hot.

Mosephus

The color is pretty much perfect. It's a nice deep clear red, it doesn't smell burnt at all, so that means this is def. a new problem.

Tate

Can you verify the temp gauge is correct? 180 will still be very hot to the touch. Not sure I could feel the difference between 180 and 250 by feel. And water will evap. rapidly at 180 as well.

Mosephus

I can't really verify if the gauge is correct, but next time I drive it I'll grab my temp gun and get some readings. The gauge in the cab seems to be varly correct since it started slipping when it got hot. Since I just got it less than two months ago I'm not sure where the gauge is picking up it's reading.

infidel

If it's truly getting up to 250 the dash idiot light should come on and the tranny won't shift into OPD.

Might want to shift into N while stop if you're in stop and go traffic.