MGB GT Episode 52 Overdrive Part 4

Overdrive oil pump is finally freed and cleaned
#MGB

[@scoobyben1979]

Hey Henry, This series has been invaluable for me to get my OD working. Did you get it sorted in the end? A previous owner for mine had bastardised the wiring loom and then added some random bits in. So I've replaced the entire OD loom along with the gearstick switch (mine is a 77 Rubber Bumper with the OD switch in the gear stick). I also replaced the OD inhibitor switch which wasn't that bad a job. Undo the gearbox crossmember and allow it to drop, using a jack, onto the fixed crossmember and then remove the access panel infront of the gearstick. Give just enough room. Ironically if the previous owner had done that the OD would probably have worked without them making the "adjustments" to the wiring.

[@HenrysGarage]

Hi Scooby, glad it was helpful. I never got around to sorting it. I was enjoying driving as is along A roads and as long as I don't go on the motorway I don't feel I need it. I also got another project car which is still taking all my time. Once the TR7 is done, I plan to go back to this as there are a few things I would lke to do on the MGB

[@heavyt749]

Did you get it working Henry ? I’m currently going through the same process

[@HenrysGarage]

I’m afraid I didn’t. I concluded I needed to take it out to sort and decided I wasn’t ready for that. Sorry

[@LowreyContractorsUK]

Thank you. I feel your pain I’m nearly finished restoring an MGB GT 1978. Wish I’d bought a two post lift at the start struggling around under it isn’t any fun. I’m up to £12,000 spent and still have to respray it and carpets. Someone has to keep them on the road 😂😂😂 and keep Moss in business Thank goodness I have a new Mercedes to drive as well.

[@HenrysGarage]

If you're anything like me, once you've got it on the road you'll only drive the Merc (BMW in my case) for long, boring trips. The MG is simply a joy everytime you're out in it

[@LowreyContractorsUK]

@@HenrysGarage yes. Correct. It’s a novelty car my Granddaughters love . I Restore the odd motorbike and tractor. Much easier as not crawling around on my back . I still haven’t got a two post lift fitted. Hope you have. Best wishes.

[@george5022]

Try the inhibitor switch on the gearbox top Left-hand side can be accessed if you take the consol out you can see the two wires and test for voltage when in 3 rd or 4th ignition eliminate thiss first

[@HenrysGarage]

Thanks George, but please explain a little more to me. I'm getting power to the solenoid, so isn't power getting past the inhibitor switch?

[@george5022]

@@HenrysGarage You say there is 12v to the solenoid, and you can hear it clicking so the inhibitor switch should be ok! put the car on 4 axle stands securely run the engine try the overdrive over 35 mph, 3rd and 4th sound a bit precarious but it worked for me, and see. was the overdrive not working before you changed things?

[@HenrysGarage]

@@george5022 I didn't say I could hear it clicking, but I also can't hear it clicking on my Triumph Stag which I know works. I am thinking the solenoid might be the issue because I'm reading 34 ohms resistance and I understand it should be closer to 10

[@danielchase3236]

How did you remove the oil pump after it was installed incorrectly? I have the exact same problem on my 1970 MGB. On my car the pump body won't come out.

[@HenrysGarage]

It’s a while ago but I think I used a metal skewer and some tweezers and a lot of time and eventually worked it loose

[@aquapet6705]

The regulator is wrong, you have the bottom part upside down! The circular filter gauze does not go inside the tube, it sits below it.

[@HenrysGarage]

That's interesting - I think this has been up for a couple of years and no one has spotted that before. I'll have to take another look at some point. Thank you

[@carstenmoore5760]

Hi Henry, Well, I think it's safe to say you have eliminated the oil pump and relief valve as far as practical. The solenoid if definitely worth another look before purchasing a pressure guage. Personally, I would remove the actuating coil from the vehicle then reassemble the entire solenoid on the bench so it can be tested with a known good 12v supply. That way it should be clear if the plunger is moving correctly or not. Can also check the coil resistance again which I think should be around 13 ohms. You can gain a little more wriggle room around the gearbox to get the bullet connector undone by disconnecting the gearbox crossmember from the chassis rails. Doesn't give you much extra, but should be enough. It's only four bolts, so worth a shot. The transmission can also be pushed over the the drivers side slightly once it is loose. If the solenoid checks out OK then I would proof load the supply circuit. As Wayne suggested in a previous episode, you may have some latent resistance which is preventing sufficient current to actuate the solenoid. A 12v inspection lamp with a 21w bulb would be ideal, as that would draw slightly more current than the solenoid as a test. If the circuit also checks out OK, I think your next step would be a pressure test. Good luck🤞.

[@HenrysGarage]

Thanks Carsten - I can tell you the coil resistance was around 34 ohms. Sounds like a plan but I've another problem today. I was trying to install a helicoil for the loose starter motor bolt. The tap snapped in the hole. I've been trying to drill it out and broken 5 drill bits in the process. I'm trying to decide what to do next. I've now removed enough of the tap that I could get the start motor flush with the housing, but I need a way of securing it. Is there an option other than persevering and drilling out the tap and then seeing if I can tap it again?

[@carstenmoore5760]

@@HenrysGarage Ohh! Not good. Don't think you will drill the tap out as the steel is very hard. If you are feeling confident with your welder you could try welding a small bolt onto the remains of the tap. Be careful not to melt the aluminium casing though! Can't think of any other means of securing the starter other than getting the tap out. Those taps won't survive any harsh lateral load, they are very brittle. When I am tapping a hole with very little space I find a small socket that fits the tap head and then use a ratchet....carefully. Hope this helps.

[@HenrysGarage]

@@carstenmoore5760 Yeah, I couldn't find a socket to fit it - I'm not confident about that weld given the room I've got available. Oh dear. We'll sleep on it

[@steveclews6557]

Is the solenoid working ??? I beleive if you short the wire you should here it click in and out ???

[@HenrysGarage]

I don't hear it, but I've got power to it (I also don't hear it on my Triumph Stag). But I am wondering if this is the problem because I think my resistance reading is a little high

[@steveclews6557]

@@HenrysGarage i do beleive i read this somewhere.ill look on the net but obv if the solenoids not good then the o/drive won't work

[@garethgoodchild2643]

Henry, that was as frustrating to watch as I’m sure it was for you. Sorry that it is still not working. I hope you checked that the pump was moving before you put the cover back on. Well done with getting it back onto the cam. As you probably read, it can be tricky. Personally, I think your next step is to take it into a shop that can check the pressure. Likely they can also check your solenoid at the same time. An hour shop time is probably worth it. The place I noted in an earlier post also gives advice over the phone so may be worth a call.

[@HenrysGarage]

You're probably right but I really don't want to go to a garage. I want to try and sort this myself (with help and advise), and since I'm only likely to be driving A and B roads in the short term, I'm not going to fuss about it too much yet. But I might be getting close to it

[@garethgoodchild2643]

@@HenrysGarage yes, no rush, it still could be the solenoid. It’s not clear whether it is actually activating.

[@HenrysGarage]

@@garethgoodchild2643 yes, I think it could be the solenoid

[@pleekh]

@@HenrysGarage I have been watching your youtube videos on this for many times. Have you tested the solenoid on the bench to see if it works? Thanks.

[@pleekh]

It's been a month since you last reply, have you fixed it?

[@LeRoiDelaRue]

Henry speak with these guys they seem to know their stuff: www.overdrive-repairs.co.uk/products.php?cat=Overdrive I had the solenoid out last week with mechanic Didn't think to look out for the ball bearing off the piston Doh!!! Cleaned the mesh Put it back together again No joy Another new lever switch No joy Next stop drain remove check wiring

[@HenrysGarage]

Nice tip KingOfTheRoad. Because I purchased another project and I'm mostly using the car locally on A/B roads I decided I could live without the overdrive so didn't fix it. I now wish I had. I'm using the car more and would like the comfort overdrive gives.

[@LeRoiDelaRue]

@@HenrysGarage cheers Henry the kotr monicker was ref my TVR Griff 500 ... Tis better to have loved and lost ... My overdrive lever switch needed replacing and it transformed the experience after 3 years of intermittently working failing and we got 46 mpg at 2900 rpm 65 mph on mway the other week Then suddenly inexplicably the overdrive bust again near Brighton ... The rest of the journey home to Liverpool was done at a max 2900 rpm max speed 55 mph in 4th. Makes a massive difference so am going to fix it Good luck!