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The overdrive is taking about 10 to 15 seconds to engage. ( I feel it used to be more or less immediate.) Having checked my various manuals I believe the overdive oil level is determined by the gearbox level, so I topped up the gearbox oil. Using 20/50 engine oil. I feel this hasn't made any difference. My manuals all showed that you used regular engine oil in the gearbox. (But the manuals were both written 40-60 years ago.)

It doesn't drop out of engagement even at low revs.

Is the oil too thin ( maybe for my worn pump) or is it more likely to be something sticking in the actuator mechanism ? By the way contrary to my service manual the only place I find to put oil into the gearbox is in the oil level plug. Is this right?

Suggestions please.

 

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Hi Jock,

            'engine' oil is perhaps the worst of the oils to put into the GB/OD. Some engine oils contain detergents for keeping the engine internals clean.

These detergents can cause excessive frothing and cause the OD pump not to work as well as it should.

It could also be that the OD pump is worn out and taking time to get up to pressure.

If it was me I would drain and refill the GB/OD (via the GB filler hole) with 40 grade GearBox oil (I use Penrite GB40).  Or you could go for an EP 90

TRy and ensure whatever you use that it is a GL4 spec oil

Roger

 

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The gearbox/overdrive oil should be 40 grade. I use Dynolite oil from Moss. 

As to the oil filler, on my TR3 the filler and dip stick are on the top right hand side of the gearbox. Access by removing gearbox tunnel carpet and then you should see a large grommet, remove this to gain access to the filler/dipstick. You may though have a later gearbox which doesn't have this filler access, in which case I believe you fill from the nearside of the gearbox from underneath the car.

The Moss catalogue gives some useful tips on checking out issues with overdrive problems, in particular the oil pump in the overdrive. Get hold of a copy if you don't already have one.

Rob

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Hi

i agree with the above advice. 

The cheapest no harm trial is to change the oil for the gear 40

if you use moss on eBay postage is free

Dynolite Gear Oil 40 Gearbox Oil - 1 Litre - EP90 & SAE40 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F183309444270

 

don’t forget that when filling either via gearbox dipstick or the left side level plug it takes some time for the oil to flow through to the OD so take a 20 min break esp if using the side level plug as it will pour out before the oil has equalised through to OD. Keep checking over an hour to make sure it’s all levelled out.

You may find an access grommet under the carpet on the tunnel to get to the side fill point.

i find it easier with the car on 4 axle stands to access this from underneath but fill via access hole takes about 2L ( but double check your book!!)

i also popped to my local vets (who look after my dogs so know me) and got a 100ml syringe that I attach some pipe like screen wash pipe that I can use to do top ups.

if this oil change doesn’t work I would suspect pump pressure.

H

 

 

4995DDBB-021A-4AB4-AA35-BB69B611CC7B.jpeg

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Thanks for all observations. Re access, I have the rubber plug in the gearbox housing but no filler or dipstick under it. So it seems filling through the side plug is correct, although inconvenient to put it mildly.

I will drain and refill as advised and see how that goes.

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If the overdrive used to engage almost immediately, but no longer does, it might be that the solenoid is faulty (pull-in coil open-circuit) and is attempting to operate using solely the hold-in coil - this takes a long time!

Ian Cornish

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On 6/28/2019 at 12:30 PM, jocklow said:

...filling through the side plug is correct, although inconvenient to put it mildly.

With the side filler plug, I found I could remove the plug from underneath using the appropriate sized spanner - what is it, 1/2" or 9/16"? Lie on back, arm at full stretch, you can feel enough to get the plug out... and back in on completion! 

For getting the oil in, though, I made a hole in the side of the transmission tunnel (¾" perhaps) in line with the filler hole through which I could pass the plastic tube that came with the container of gear oil and in to the filler hole.

A lot less faff than taking the transmission tunnel out, or trying to get the oil up from underneath and in to the filler hole...

As said previously, though, do take your time.

IIRC, if you want to get all the oil out, you'll need to drain the g/box and OD separately as the OD won't completely drain/empty back into the b/box if you only remove the g/box drain plug.

Nick

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I passed a plastic tube through the large hole in the tunnel down to the filler / level plug hole, other end onto a funnel, into which I poured the correct quantity of oil.

                                          20180724_133303.thumb.jpg.9235e5d682530d4a97e450aff1cff429.jpg                                        20180724_132202.thumb.jpg.e8266d3d605ffb3b76c5d47926601cd8.jpg

Bob.

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17 hours ago, Drewmotty said:

.....I fill using one of these. Takes a few fills and a fit thumb though :unsure:

 

2346C3F4-E5AD-4BFD-A611-0F42FDD0263F.jpeg

+1 on my TR6. TR2s have the top dipstick and filler hole.

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