Auto gearbox issue after head gasket failure, Auto gearbox issue after head gasket failure Options

[davewuyts]

Hi there everyone - I just need some collective wisdom from all you wise ones out there.
I have had a traumatic month or so with my auto gen6 JDM ST202 convertible. After carrying out several repairs on the roof etc I was looking forward to the warmer weather when the head gasket went, along with a couple of oil seals. A bit of a mess.

So, this being beyond me, I put it into my faithful garage who I've been going to for years. It was returned to me a couple of days ago, all seemed fine and I seemed to have gained a bit of torque from before!

However, now I have it back, it's driving nice APART FROM the other day it suddenly slipped into neutral at the lights, the rev counter suddenly shot up as it lost the resistance of holding the car on the brake.. I've also noticed an occasional slight delay in picking up from a standing start. 98% of the time it's fine. I can't see anything obvious, there are no leaks including from the auto transmission fluid.

Before I go back to chat to the garage (who I get on well with) I want to just establish whether anything in the Head Gasket Work might affect the gearbox in any way. Can't imagine it myself but thought it was worth a heads-up here.

Dave

[davewuyts]

An addition from tonight - put foot down on motorway and didn't find a gear. A big loud revving and then I lifted off and we kept going. A problem we have...

[mkernz22]

They probably flushed the transmission while it was out and that usually clears out a lot of the build up from over the years. If it's a high mileage transmission, then they sometimes start slipping after flushes

[Box]

^That. Or the fluid could be low or the filter is clogged. Just another reason I hate automatics. They all inevitably fail by design, frictions slip and eventually they get so worn they need the grit to grab until there's nothing left and it needs a rebuild. Think of it as the clutch on a manual, but terribly more involved to repair.

[davewuyts]

I've just had a look through my considerable documentation and found that it's not been changed for years. The level is not low and never has been. I've missed it somehow (I've only had the car for 3 years). So there we have it. It's not a very high mileage car, only about 86,000 miles on it. Will get it changed on Friday. Hopefully that will do it!

This post has been edited by davewuyts: May 18, 2016 - 8:43 AM

[Box]

Only 86,000 miles it should still be ok. Another possible cause are the shift solenoids or valve body are gummed up.

[SwissFerdi]

Make sure they do the change correctly, as the only proper way to go about it are several flushes. What I mean by that is, the proper procedure is to drain about half of the existing transmission fluid, then top up with new fluid. Drive and then repeat, draining and refilling twice more. After three times the fluid should be mostly new. Like mentioned above, if all of the fluid is replaced at once the clutch packs might slip.

This post has been edited by SwissFerdi: May 18, 2016 - 7:01 PM

[Box]

Make sure they use the proper fluid as well which should be Toyota ATF Type T-IV if memory serves correctly, I'd double check me by looking in your owner's manual or someone can come in and say for sure. You can get it from any Toyota or Lexus dealer, but if you can buy off the U.S. Amazon site I found it there for $67 for 12 quarts which makes it really no more than generic stuff at the store. I forget capacity, which is also in your manual, but like Ferdi said you'll need to do a gradual flushing with new fluid so you'll need more than just capacity.

[Bitter]

You can drain and fill it yourself at home if you have a set of ramps or even with the tire change jack. Drain the fluid into a pan and pour it all into a gallon jug then pout clean new fluid into another gallon jug and put them side by side to match the level. Put back in what you drained and your level will be the same as before. Drive the car and do another drain and fill, then in a week another, you'll have nearly all the fluid changed by that time. Then after do it once a year and you'll always have essentially new fluid.

[davewuyts]

Transmission oil is changed. It seems to have done the trick. I'll let you know if something else becomes apparent!

So new transmission fluid is in, car drives lovely but there is still an occasional fault. Not sure if you think it can take a few days to settle down or not... I'm hoping so. However the symptom of the fault is a delay in picking up the gear very occasionally, normally from a standing start. Once it's grabbed the 1st gear it all works fine. No noises, no warning lights, no vibrations. Not sure what to do next - though I'll give it a couple of days to see if it settles down.

[davewuyts]

Well it seems to have settled down now. It took a few days. Hopefully I will have no more reports to bring!