I was hoping someone may have experience with an issue I'm having with my turbo 400 on my recently acquired 69 Firebird 400. Unfortunately I have no previous history of the car so don't know when the transmission or engine were last rebuilt.
Once the transmission is hot it won't engage forward gears unless I apply some revs, then it seems to engage ok, reverse gear engages instantly no problem and I've notice no issue on start up with either. I recently changed the ATF and filter and have since double checked the ATF level. I did notice when I changed the ATF and filter that it had a build up of silver sludge in bottom of pan but didn't think much of it at the time. Also it had a cheap aftermarket trans cooler added which I have since removed and I reconnected the trans oil lines back to the radiator.
Any ideas what the issue may be? Appreciate any feedback, I'm wondering if I should reconnect the oil cooler?
The Doc diagnosed that correctly. That silver sludge is clutch pack. I have been through 3 rebuilds, so I am really familiar with it. You may want to replace the torque converter as well, or drain and filter it to see if it has a bunch of crap in there. My first joy of this experience was when the local muffler shop routed my exhaust correctly, but I forgot I had the speedo-cable in the incorrect place. Melted a hole through it, and pumped all my tranny fluid out.
You'll get to know a lot about your car now. Having been down this road three times, you'll want to pull the entire engine with the trans. Just easier that way, unless you have a lift. Once you have it out, you can replace all the stuff you don't like.. new radiator, clean up the engine compartment, etc. On my last rebuild, I took the opportunity to weld all the holes shut, clean and paint the trans tunnel. Welded up all the holes in the firewall and routed my trans cooler lines where I wanted them. The originals were gone. When you go for the rebuild, take the opportunity to do all the little stuff in the engine bay. Your back will thank you for it.
Just a story to consider...One time I inherited a TH400 that was full of sludge. I think it actually had water in it and corrosion. It took 3 fluid/filter changes to clean up all the crap that was in there. The filter would plug up and the car would quit moving. After the 3rd fluid/filter change it seemed to run fine.
Re: Turbo 400 not engaing forward gears when hot
[Re: Bob S.]
Thanks for the feedback, I really appreciate the guidance.
I guess safest path is to rebuild which I haven't done before, do you think this is something a novice could handle?
How hard is it to just remove the tranny by itself without motor, as I have a four post hoist with one of those rolling jacks?
If I removed the motor and transmission I'd probably have to consider rebuilding the motor as well. The engine loses oil pressure when hot and at idle goes down to 5lbs pressure which I presume means engine rebuild? I'd be interested in your thoughts if this means a total rebuild?
Not planning to keep this car long term so was hoping not to have to do any of this but I guess difficult to sell with faulty trans and bad oil pressure.
I think you answered some of your own questions. You probably need to have it rebuilt. And in my opinion that isn't a job for a novice. I would offer that a good professional rebuild would be worth the money. Unless numbers matching etc is important you can also find many "solid" used transmissions and save a grand. But you might also end up rebuilding that one too. Hmm... For my money (which this isn't) get is rebuilt and move on.
But you brought up an interesting point about not keeping the car which s something you need to figure out for yourself. Depending on how nice the car is as it sits you probably won't get your money back on the engine and tranny rebuild. My experience is that at best you will break even, which is totally unfair, but common. The exception would be a car that is very nice but not running. Consider the engine and tranny rebuild will be $7500 +/-. Add that to the cost of a solid non running car and you come out where? Now here is something to consider... a nice running and driving car, in any condition, is way way easier to sell and get decent money for. A non driving, oil leaking and smoking car can be a tough sell. Many factors apply of course but that is generally true.
I asked the same question here about pulling the engine and leave the tranny in, and the advice was to just pull as one item. After doing this a number of times, I wouldn't do it any other way. Lots of torque specs to take into consideration when getting it all mated back up. Being able to do this outside the car was simple, I am not so sure with the trans in the car.
I had the same problem with the 400 I had in my car. It was "rebuilt"... I use that term loosely. At idle, oil pressure was around 5 lbs, driving it would be around 20-30lbs. Drivability was horrid, and I decided to just pull it and have it completely rebuilt. When I had the engine disassembled, (Gunderman Performance) I grabbed the pile of parts that came out. I found re-used bearing, a mix of replaced parts, and pistons, all kinds of crap. Deciding on the rebuild was an investment to me. I love this car, how it drives, how it feels and how it looks. I dumped about $9,000 into a full rebuild. I wasn't worried about numbers matching, as nothing on the engine matched. I kept the iron cylinder heads, and other original parts, but did a full upgrade. Original intake was long gone when I got the car, so not much to keep. I'll post a picture of what I found in my pile of parts (worst part). But I found the engine wasn't bored correctly.. overheated so they the measurements made them hour glass shaped. There was a full .015" of difference between top and middle. I should have this engine back in a few months, and getting it on the road again. Until then, I have fun in my 68 C20 and my 57 TBird.
Removing the trans. alone with the right tools is no problem in fact if you were paying a repair shop to do it that is what they would do. I have done many on my back and with a lift is much easier. As far as the oil pressure I assume this is with a cheap aftermarket gauge and not a professional mechanics gauge. Is the original warning light still hooked up and not lighting up at idle?. If you want real numbers get ahold of a professional Gauge and you should see a minimum 10 psi or more at around 1k rpms. If still a little low you could try running some 15 40 or 50 synthetic along with a separate zinc additive. As long as the motor runs and sounds good and you don't plan on keeping long enough to recoup rebuild costs I would just run it. It does not take a lot of oil pressure at idle to keep a motor happy as long as it comes up appropriately with rpms. By the way I had the exact same thing happen to a 70 impala winter beater I had back in the 80's. Being a crazy young guy I drove home about 15 miles on back roads with snow on the ground at 1 in the morning in reverse. Boy did I have a stiff neck in the morning. The next day forward worked like there was never a problem until it got hot again. Lastly if you changed the fluid yourself with just a drain and fill most of the old fluid is still left in the trans. and converter. if it was burnt and foamed hard, one last try would be to take it to a professional shop that uses a flush machine. I used to do these in the shop that I ran and it will change and flush out every drop of the old fluid. but there are no guarantees it will fix the problem and most likely the trans is done.
I think I will just pull the trans and attempt a rebuild myself, I'll replace the torque converter as well. I've had a look around online for torque converters and I noticed a number of different bolt patterns, is it 10 3/4", 11 1/2" or 12"? The engine is a 1970 Pontiac 400.
I'll make a decision on the engine rebuild later. Its a nice car but I have another 69 which I'm planning to restore so thought that would be the keeper and I would flip this one.