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BJ8 overdrive intermittent

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RobWarren

Jedi Hopeful
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I've been finding on the last few trips that I've done, that the overdrive works wonderfully well when I start out - it engages when asked and if I forget to switch it off when stopping at lights, it automatically engages again when I get back up into third.

However, after a decent run when everything is warm, it stops working.

This is whether I'm getting back onto a decent road and switch it on in 3rd or 4th or even if I've left it on and am getting back up into 3rd or 4th.

I've trawled the forums but can't seem to find anyone with the same problem. I have a feeling it's a pressure-related issue - perhaps the pressure isn't being built up when everything is warm and fluid - but the overdrive is an area I know little about so I figured I should ask the Oracle that is BCF.

Rob
 
I had the exact same problem with my 65 BJ8.
After the car got hot such as after a long ride, the overdrive didn't want to engage any longer.
The fix for me was to drain the o/drive and transmission and fill it up with 60w Valvoline VR1 racing oil. You can use 50W in the colder months.
....
I suspect that the 60w oil makes up for wear/poor fit in a seal such as in the accumulator. I notice that the parts have been redesigned in the accumulator ( per moss catalog ) so I suspect that there was an improvement made in these parts for a very good reason.
It is the easiest and cheapest way to solve this problem with the o/drive rather than removal , rebuilding, and replacement.
... It has now been working flawlessly for 16 months since I switched over to 60W Valvoline.
Ed
 
Rob, It certainly sounds like a pressure problem. Be sure your fluid of choice is topped off (and I don't think it matters what you are running with this sort of problem). If you cannot make or get access to a pressure gage with the adapter you need to tie into the OD ( I might be persuaded to lend you mine, which I made a while back when I was having every OD problem in the book), you are at a big disadvantage. It will answer the pressure question by one test ride, or if you trust jack stands you needn't even leave the barn. There is a super good series of articles on all aspects of OD function and rebuilding on the Buckeye Triumphs web site( I've put the URL below ). Read it and become an OD expert. They fellow who put this series together will be remembered long after he is gone. It doesn't get any better. There is a pressure relief valve inside the OD that can be inspected and perhaps repaired if the problem is a worn spring, ball bearing or seat, without removing the OD or the gearbox from the car if you don't mind a few contorsions, and have some patience. I also have an oil pump puller (another simple tool that can be made)and Both these items are small and I would consider lending them out if I was re-assured of getting them back. This forum and the folks who post here have been a big help, and since I don't have any British car experience except for my one restoration, I can't be as helpful as Keoke or as Dave Russel was. But I have this big box of Mowog tools, most of which I can't identify, and I know someone out there needs 'em. My guess is that you might not need the pump puller, but I'd suspect the pressure relief valve being dirty, or worn. Let me know if you want to borrow the gage.

https://web.archive.org/web/20030401182927/www.buckeyetriumphs.org/index_technical.htm
 
Try an easy (possible) fix first: get a new O/D switch (or swap with a known good one). At least try jiggling the switch when the O/D cuts out. I've had three switches go bad over 100K miles.
 
Well I agree that you have a pressure problem Either a worn pump or a defective return valve. However, as ED k pointed out you may be able to compensate for the wear by going to a heavier weight oil. Regarding technical guidance on these overdrives in addition to the Triumph report go see MR Finespaner he wrote the book.He is one of the few who will tell you exactly what is wrong for each of the typical malfunctions seen with these OD's.---Keoke
 
Rob:

Could be oil, but I think it's probably the solenoid.

My OD acted up intermittantly for years. Suddendly it would fail to engage, and then not work for hours -- then suddendly start working fine and stay that way for days. Finally when it quit for a couple of days I took the tranny cover off and drove the car. The solenoid was just plain not pulling the actuating arm with enough force to engage -- if I pulled on the arm manually, the unit engaged perfectly.

The problem is those tiny contacts inside the solenoid that need to close to energize the pull in coils on the solenoid. The pull in coils are very low resistance and need plenty of current to generate the force needed to pull in the OD. All you need is a few ohms of resistance accross those contacts and the solenoid will not do its job. Resistance of contacts comes and goes, which makes the problem intermittant.

If your OD fails to engage at all when you ask for it, don't ignore this solenoid. Bad oil pressure in the unit due to thin oil or leaking pistons usually produce different symptoms: the overdrive slowly drops out of OD or gets hung between OD and direct drive. Or, it engages, but very, very slowly. Or, if you give it lots of gas, it starts slipping into direct drive.

Hope this helps,

Bill S
Albuquerque, NM
 
Bill's theory can easily be checked if you pull over to the side of the road when it's hot and put it in neutral with the key on and engine off. Move the shift lever from left to right. You should hear a loud click of the solenoid if it is pulling up. If it is silent, then the solenoid is not pulling. Try it when it is cold and listen for the click. The solenoid is easy to replace and costs about $50.
 
Ni TMK that test will not confirm this problem. In this case the solenoid is operating as it should but fails to set the actuating valve correctly.--Keoke.
 
I had similar symptoms on a road trip a couple of years ago. Diagnosed it as the O/D relay. Carefully disassembled the relay and cleaned the contacts, and the problem was solved.
 
Several different things can cause similar symptoms. Any of the things people have suggested might fix the symptom or the problem. If you are going to drain the oil and run a heavier weight stuff, and that fixes the SYMPTOM, you still have a problem. The chances are that the solenoid either works, or it doesen't, although it is possible for the solenoid to drop out when it has been activated (the OD works initially), when it gets hot, but guessing at that is what leads to buying a solenoid, putting it in, rigging it, and if it doesn't fix it, you still want to know what your pump pressure is. Test it by listening for the click as you move the shift lever left to right, as has been pointed out. Do this when it is hot (pull over & shut off the motor). If you still get a good click, forget the solenoid itself. It is also not likely to be riggng as it works initially, unless your rigging is right on the edge of operating the operating valve, and when it heats up and things expand a little... it is possible. But the pressure question will always lurk if you don't check it. The only reason everyone always wonders about it is because they don't measure it. Once the tunnel cover is off it takes about one minute to install a gage and you are off for a test ride. Troubleshooting and eliminating the easy to fix stuff gets way easier if you know whether or not you have proper oil pump pressure.
 
Well Yeah Roscoe, but you are not going to be removing the tunnel or running pressure tests on the side of a carriage way. You can get home with out an OD--Keoke
 
Rob,
Your symptoms sound exacly the same as mine from a couple of years ago. I described my overdrive troubles and the solution on this forum.
The problem was loss of pressure once the oil reached operating temperature and replacement of the accumulator fixed the problem.
I got the parts from AH Spares in the UK. Members of the Austin-Healey Owners' Club of New South Wales will recommend an overdrive specialist in Sydney.
Good luck,
Alwyn
 
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