After a long-term rebuild (are't they all - lol) I cannot get the overdrive to work. So far I've drained & refilled the gearbox/overdrive oil (EP90), replaced and adjusted the solenoid, removed and cleaned the operating valve and removed/cleaned the filter, but still no joy. I was going to remove and clean the accumulator but don't have a socket large enough - does anyone know the correct size, as I don't want to purchase the wrong one (if indeed I can find a supplier). The accumulator plug is the large brass one underneath the overdrive unit.
The only other component I couldn't remove was the non-return valve (also accessible from underneath). Removing the access plug/spring/ball bearing is easy, but a Churchill tool L213 is required to unscrew the actual non-return valve. From what I've read this valve and/or the pump behind it are likely reasons why the OD isn't kicking in, so I'd really like to gain access, check and clean them. Does anyone have access to such a tool or have any advice as to how they managed to remove same themselves ?? The gearbox/overdrive have only covered 65,000 miles so I don't think it likely that the internals have worn out. Any advice/help would be much appreciated. Thanks evryone in advance.

 

Captain Q wish you were in NA we could help you. Tool L213 is a oil pump body key--is this what you seek? The accumulator removal tool s L 182 but before I tried anything I would put a pressure gauge on the system. Take a look at Tool Loan | Jaguar Clubs of North America and make sure what you seek. The OD for a MK2 should be in the 60s catalog (ue) but you may have a later one. We have all of the tools and know some folks in the UK with modest holdings. Let us know.

 

Thank you Coventry Foundation. Your assistance is appreciated. I am considering making my own 0-1000 psi gauge (I can buy a new gauge for less than $10) to test the pressure, but do you know whether I would need to adapt a new operating valve plug (thereby still allowing the valve & spring to operate), or is it enough just to remove plug and screw the gauge in to test pressure ? Kind regards Keith

 

The shop manual for the compact type shows simple removal of the plug and a hook up of the test gauge. You only need a 1000 psi unit as 800 is stated as the desired pressure. Indeed the Churchill test Gauge for this goes to #1200 but it is also used for other tests. Best of luck!

 

Many thanks for your advice - I'll post outcome in due course - it may help other owners with similar problems.

 

Hello again everyone,

As promised I have an update regarding my lack of overdrive, and I'm hoping someone with deeper knowledge than me can advise. Earlier today I connected a 1000psi gauge to the bottom of the operating valve, started the
car (which was on axle stands) and when fourth gear was selected (overdrive NOT switched on) the pressure rose quickly to around 340psi. I then selected overdrive and, initially, the pressure dropped to about 260psi and, after half a second rose to 360 momentarily, before settling back to 340psi. Overdrive still did not engage.
Looking at the official Laycock manual they state that a 3.8S should have a pressure of 470-490psi and a MK X should have 520-540psi !! They don't say what a MK2 should read (and neither does the official Jaguar
Service Manual) but I presume it should be similar (or identical) to the 3.8S. To complicate matters further my gearbox/overdrive came from a 240 model (JCN gearbox which, according to Jaguars parts manual, was common for all later cars with no different ratios between engine sizes). The only difference I can see is that the 2.4 uses a different Accumulator spring (in the overdrive) to the 3.4 & 3.8 (presumably weaker, which will probably result in a lower operating pressure ??). It appears to me that the pressure readings I obtained are nowhere high enough to operate. I have read somewhere that it's possible to increase the pressure simply by putting washers underneath said spring - a 1/16" washer apparently adds 50psi ?? My first job however, will be to remove the accumulator and check that a) the spring isn't broken and b) that everything is clean without blockages.

I'd welcome any comments or advice regarding the aforementioned. Is it also possible that the NRV and/or the pump could be at the root of my problems ??

Thanks in advance.

 

You are on the right path. Either there is a leak in the accumulator or the pump is not up to form. You need more pressure as you said and you can use the pressures from the other units

 

I'm watching this thread with interest. I have a Compact A Type OD in my 3.8S that was reconditioned many years ago that is only now being commissioned after a long restoration. All electrics are correct & new solenoid behaves as it should (also have new GB switches). OD does not engage. I've been told that the suggested lever with pin in hole solenoid lever adjustment is hopeless & inaccurate. Your 470-490psi is one of the pressure ranges I've been given.

Good luck & keep us informed. Also let us know how it goes with solenoid lever adjustment. Seems a black art.

 

Hi Glyn,

I tried a number of times to adjust the solenoid using the 'pin in the hole' method, thinking that was my problem. Having cleaned the filter (not dirty) and the operating valve (again clean) I was advised that the best way to
check was by using a 1000psi gauge, in place of the operating valve plug (bolt, cap or whatever you want to call it). It's important though that you keep the valve, spring and ball bearing in situ, so I contacted Overdrive Repair
Services in Sheffield UK and they sold me just the adaptor to screw in, as I already had a gauge. As my previous post states, the pressure was too low to operate the system (looks like it should be between 470 & 490
psi). I've just bought a 11/2" impact socket, to remove the Accumulator plug to check the spring, as I suspect after 50 years it may have weakened (apparently its this spring that basically controls said pressure.
During my searches I came across a really informative article on a Triumph website which stated that for every 1/16" washer placed under the bottom of the spring in the accumulator you'll gain around 50psi - so I'll probably
try two/three in mine. A lternatively, SC Parts sell the spring - but it's £38 !! Cars left the factory with washers/shims so, provided you don't go over the top, it seems a sensible route to take. I'll post again after I've done the
aforementioned. With regards the solenoid adjustment - if you connect a gauge you'll see whether the solenoid is doing its job, as the pressure drops slightly when the solenoid is energised and then goes back to its
un-energised state (in my case 340psi).

Regards Keith

 

Thanks CQ. I saw my OD running on the test rig 20 years ago & pressure was OK. So I'm hoping it's only adjustment.

 

Hi again,

If the unit hasn't been used for 20 years I suppose its possible that parts have temporarily stuck together ?? I'm particularly thinking of the clutch linings - I read somewhere that a good bang on the unit with a rubber
hammer can work wonders ??? Might also be worth taking the operating valve out and checking that for any blockages (the small hole near the top is VERY small and can easily get blocked). Good luck !

 

Cpt.Q banging on the O/D is a solution when the clutches have stuck in the engaged position but you are on the other end of the problem. You most likely have a bad pump which is a common problem.

 

Hi again CF. Thank you for your comment - I wasn't referring to my problem, but that of Glyn M Ruck - who's overdrive, despite a long-ago rebuild, is not engaging. I understand what you say regarding that being the possible
solution if stuck 'engaged' - I stand corrected. It does seem, however, that 'something' may have become stuck or blocked. Like I said to him, his best course of action (as indeed was mine) is a pressure check.

Kind regards - Keith

 

Hi again All,

Latest update regarding overdrive. Having checked the pressure, as mentioned previously, which registered 340psi (a slight drop when solenoid operated and then returning to 340psi) I decided to insert washers underneath
the Accumulator spring in an effort to increase the pressure. Incidently the large brass nut/plug which you need to remove to access the spring/piston is actually 1.5" AF. Initially (bearing in mind that my pressure was
probably around 150psi lower than optimal) I inserted three washers - each being 1.35mm thick - total approx 4mm. Upon checking the pressure - once the oil had been put back into gearbox/overdrive - I achieved a new
pressure of 420psi. Still too low. What I did notice, however, was that the pressure did NOT drop and then rise as before, it just stayed at 420psi. Drained gearbox/overdrive again (I hate the smell of that oil now !) and inserted a further three washers (now 6 - equating to 8mm). Refill gearbox/overdrive & recheck. Pressure now 470psi, but still NO initial pressure drop when OD selected - and no overdrive.
Since then I've researched various websites and have come to the conclusion that the Accumulator spring is compressing so far before it can compress no further. It's likely that the Accumulator piston is not moving along its bore far enough to reveal the holes to allow the oil to move along the system ?? As previously mentioned, my gearbox/overdrive is actually from a 2.4, and this model used a different spring to it's larger engined brothers - I'm now thinking that this fact is a part of my problem. Therefore, I have ordered a new 3.8 spring to try and will report back when I've tried that.

 

Thanks for keeping us informed. When you get everything in spec I will be interested to see how you set the operating valve lever. Time & time again I'm informed that the pin in hole method does not guarantee engagement even when all is OK.

Here is a Healey 3000 Type A Compact. Same overdrive ~ different solenoid location/orientation but the principle identical & the comment the same regarding the pin in hole method.

EDIT: My car is fully built & while I would love to do another pressure test the port is not accessible without a major strip.

https://video.ultra-zone.net/watch?v=Gdsjd4Q_JFM

 

Hi Glyn,

I did have a conversation with David Twigger at Overdrive Spares, Rugby, UK. He's a very knowledgable person on these matters and when I informed him that (after I had installed the washers) the pressure no longer
dipped & then recovered when the OD was engaged, he suggested that the solenoid may not be set up correctly. Apparently, when the operating valve opens (as a direct result of the solenoid operation) the oil starts on its journey to the operating pistons, resulting in the momentary pressure drop. My overdrive currently has the 2.4 accumulator spring fitted (with six washers) so I want to change that anyway for the 3.8 version (it actually arrived in the post earlier today). Obviously I'll try the new spring first and then, if that doesn't resolve the issue, I'll double-check the solenoid. David did suggest moving the operating lever manually from inside the car with the tunnel cover removed - that may be possible on some other makes of car but on the MK2 there isn't room (I'm reluctant to climb under the car to do so with the back end on axle stands !). David also suggested that, as the car has been off the road for some years, the clutch parts could be stuck. One solution to that possibility is to drive in fourth gear with overdrive selected, dip the clutch and then then release harshly - I've tried that route but to no avail. I'm planning the spring change tomorrow so will post any updates. Thank you, Glyn, by the way for the Video Link. Regards - Keith

 

UPDATE: Still no overdrive !! This morning I drained the oil AGAIN and replaced the accumulator spring (a measurement beforehand showed it to be 4mm longer than the 2.4 version fitted). Re-filled the oil again and started the car up (on axle stands). Pressure slowly went up to 550psi - brilliant. However, selected overdrive in fourth gear and still not working - as previously, no pressure drop just maintaining 550psi.
As per my previous thread, I then turned my attention to the solenoid adjustment. I screwed IN the adjusting nut a few turns and re-checked - 'HURRAH' - a pressure drop and then back to 550psi, when fourth gear overdrive was selected BUT still no overdrive !! So - it appears that the operating valve is doing its job, which means presumably that the oil was making its way up to the operating pistons but it's obviously NOT moving the important clutch parts - DAMN. I then lowered the car and took it for a drive. I then did as Daivid Twigger suggested, and dropped the clutch whilst overdrive was selected and released it harshly several times, in the hope that the moving parts would start moving - no joy (Sigh !!). I'm now going to jack the car up again (very securely) and attempt to move the operating lever (which the solenoid is attached to) by hand with the wheels turning, just in case my adjustment isn't quite right. I think I'm getting desperate now as I'm not relishing removing the overdrive from the car. Does anyone have any more suggestions that may help me to resolve this annoying
issue - I'm getting sick and tired of jacking the car up and climbing underneath !!

 

You have my sympathies. I saw my overdrive running on the rig & behaving itself all those years back. Now it's in the car & no joy. The solenoid is working as it should & reads the correct high selection current & low maintaining current to hold engagement. The company that did the rebuild is no longer in existence. The trouble is at the Southern tip of Africa there are no overdrive specialists left. Hopefully someone in the Club can give me advice.

 

Hi again Glyn,

The first thing that David Twigger asked me was "Has is been off the road a long time ?". In my case, yes, about 15 years. He stated that if the pressure dropped and then returned to its pre-engagement pressure when the overdrive was selected, it indicated that the oil was enroute to the operating pistons and that it was likely that the clutch slidining member (presumably No 57 on parts diagram) was stuck. That's why (as he suggested) I have just been for another drive, dropping the clutch in order to get the parts moving - still no luck I'm sad to say. Unless someone comes up with a 'magic bullet' I'm just going to have to 'bite the bullet' and take the overdrive unit off - I'm told that once the rear of the engine is dropped, in order to reach the top bolts/nuts, it's fairly quick to remove. The problem, apparently, is getting it back on - the spline are difficult to line up.
God luck with yours - it may be worth trying the clutch-dropping excercise ??

Kind regards - Keith

 

Hi Keith,
Yes I'm told you can get the OD out with Engine & GB in place if due care is taken & done correctly (split at the right point) so as not to spill bits into the gearbox. Is a trip to Rugby not worth it to let the pro's fiddle before you remove the unit? I know we all like to DIY & save money. I'm going to try the clutch dump procedure. I will have to be naughty. My car is not registered yet. My car has the PAS engine stabalisers so I will have to undo all that to get the OD out.
KR
G