3.8 L problem

[duggers]

Hi!
My wife has a 94 3.8 V6 with an automatic trans; a very basic car. A little over a year ago it started to do this: the engine would suddenly go up a thousand RPM or so while the car lost power. I'm no mechanic, but it felt as if the transmission was slipping or something. I took it to AAMCO, but they said the transmission was OK, so then it was on to a dealer, who eventually decided it was blown head gaskets. Had those done (expensive), and the problem seemed solved. But now it's starting to come back again, very gradually. My warranty on the repairs runs out in 10 days, so I'll have to go back to the dealer, even though the problem is so intermittent that they probably wont be able to duplicate it.

Has anyone else had symptoms like this, and if so what worked for you?

Any advice appreciated.

[hmongstang]

welcome to 3.8mustang.com

[Los]

I don't have a clue. Did your car bellow white smoke from the tail pipes?

[duggers]

No smoke, no engine oil loss. Took it back to the dealer and they said that there might be oil residue in the cooling system left over from the head gasket repair. This messes with the thermostat, which messes with the whole cooling system control thingie, causing stuff like the fan coming on early, which can cause the engine to surge (think I have this right...). They're cleaning out the cooloing system and will get me to bring it back in a couple of weeks to make sure there isn't any more oil in the antifreeze. Hope this solves it, hope it might help out anyone else looking for engine surging causes.

[cte55057]

Originally Posted by duggers

No smoke, no engine oil loss. Took it back to the dealer and they said that there might be oil residue in the cooling system left over from the head gasket repair. This messes with the thermostat, which messes with the whole cooling system control thingie, causing stuff like the fan coming on early, which can cause the engine to surge (think I have this right...). They're cleaning out the cooloing system and will get me to bring it back in a couple of weeks to make sure there isn't any more oil in the antifreeze. Hope this solves it, hope it might help out anyone else looking for engine surging causes.

Been there done that. flushed cooling system after we replaced head gasket-another problem and a misdiagnosis after # 3 injector was constantly dumping fuel in # 3 cylinder. I replaced computer solved problem. Trans problem remained. When driving along normally the trans will disengage and engine will rev up 1-2000 rpm and then jerk back into gear. tranny fluid looks fine and smells fine does not look like it has ever been really hot. We live in very flat regions, but after driving in hilly conditions this problem seems to be more prevalent. Does anyone have anymor advice. this seems to be a common problem

[stang_racer20]

if you want my opinion duggers, sounds like you got jacked on the repairs, cause nothing they said would explain an engine surge like you explained. i am a certified mechanic, went through schooling so I do know a good bit. i cant really tell ya a diagnosis without seeing it myself, but it does sound like a transmission problem. You would know if you had a blown head gasket, fuckin dealerships!