problem with my transmission...

[joojoobee]

hey guys,

can anybody tell me why my automatic transmission pops out of overdrive on my '99 rodeo, after driving it for few miles. After that it wont go into overdrive at all. Overdrive usually works for the first few miles every time I drive it then it seems like it doesnt want to work until i let it cool down for a few hours. All other gears shift perfectly fine. Its just the overdrive i have a problem with. It happened before we got our fluid/filter changed about 6 months ago and it stopped happening for awhile and now its back.

Could this be due to a bad overdrive solenoid?

Could this be an electrical problem(bad alternator, etc.)?

Would a flush fix this problem?

Let me know...Ive been trying to diagnose this problem for a while now. Thanks!

[amigo-2k]

it could be due to low tranny fluid.

[Ramblin Fever]

What's the maintenance history on this tranny?

If your last fluid/filter change came after a long interval, i.e. more then 50k miles or so, it may be due for another fluid change.

It does sound like it's low on fluid too - I would have that checked asap; these GM 4L30-E auto tranny's cook VERY fast if they're allowed to be low.

Alternator voltage could cause issues too; check your volt output while having the alt under load, if it's less then 14v, find a new alt - but be cautious as to which one you choose.

[joojoobee]

Thanks for the replies guys,

Im pretty sure, because im the second owner, that the transmission was not serviced like it shouldve been becuase when i got the fluid/filter change 6 months ago, my mechanic said the the fluid/filter were quite filthy. I will probably go and get flush and hopefully that will work. I will also try to get that alternater checked too. Ill update once i get these done.

thanks again!

Larry

[joojoobee]

well,

i just got my tranny fluid drained and filled...didnt help. Then i got my alternator tested and its putting about 14.05 volts...Isnt the alternator supposed to be putting out more?

Other than that my overdrive still pops out of gear when going 65 mph or higher. Sometimes it doesnt even go in at all. The transmission guy said there is a very small leak but would that be causeing some lost in pressure?

Anyway any answers or replies would be great. I hope this isnt an internal issue but if so, that would suck. I also went to the isuzu dealership and explained the problem to him and he said it sounds like an electrical problem.

[Ramblin Fever]

Any *small* leak on these tranny's is major - these transmissions in particular are VERY picky about ATF level, do NOT let it continue to leak. It may be minor while idling, but moderate while driving.

Did they do a drain/refill? or a flush?

Just re-read one of your posts, in which your fluid was quite dirty when you purchased it 6 mnths ago, this could be the cause of what you're seeing now. How many miles did it have on it 6 mnths ago?

[joojoobee]

They did a drain/refill few days ago and it had about 113,000 miles on it 6 months ago when the filter was replaced. After that the symptoms(overdrive popping out) went away... and recently(2 months ago) it started happening again. They say the small leak may be coming from a seal or something behind the mode sensor...

Do i need to replace my mode sensor? Anyway thnks for the rply.

larry

[Ramblin Fever]

Probably the same seal I had replaced - is it a very mild drip on the driver's side, just behind the range mode sensor?

If so, it's actually coming from above the mode sensor, and probably the seal from the floor shifter to the top of the transmission - it's a $5 part and an hour's worth of labor, no big deal.

If at 113k, that was the first ATF drain/refill, could be that the ATF was depleted and toasted the tranny - actually VERY common on these trucks if the ATF is not changed prior to 50k or so miles.

I would suggest another partial drain/refill, I know it's tedious, but it's worth spending another $78 or doing it yourself prior to finding out if a $2-3k dollar repair is in order.

Try doing another drain/refill, if that doesn't work, you could be looking at a new transmission. Word of wise, do NOT have your current one rebuilt - won't last but maybe a year, if that. They are not good canidates for a rebuild, as many do not know how to properly fix them.

[Gizmo42]

Do NOT do a flush, just some partial fluid changes. That will kill it quick if its not already bad. Thats advise from the Isuzu Guru JLEMOND.

Getting a good rebuilt one can be tricky. Mike went through 4 or 5 rebuilt ones in about a month. The builder eventually found out that the aftermarket valves they were using werent right. It has to be built using only Isuzu OEM valves.