I own a late 1967 Mark 2 3.4 with all synchro and ‘type ‘A’ compact overdrive.’ Here is my question. I went to visit my mechanic today for and oil change. While the car was up on the lift I asked him to check the oil level of the gearbox. To my surprise, he had to add between 2 and a half & three pints to bring it up to full level. The car had been driving fine, and when I engage the overdrive stalk, it goes into overdrive in a timely manner. When I got home I consulted the Jaguar factory service manual as well as my original owners manual. Interesting… I get different capacity numbers on different sources. The factory service manual supplement for the all synchro does not even specify capacity unit, just that it used 90 weight gear oil. The capacity page for the older style non synchro model specifies 3 and three quarter pints. My owners manual says 4 and three quarter pints, and does mention that if the level is checked after a ‘long run’ a substantial quantity of oil may be in the overdrive unit. I really do not think I’ve been driving around lately with less than a pint of oil in my gearbox. According to the owners manual, “if the oil level is allowed to drop too low the operation of the hydraulic overdrive may be affected.” The good news is, my overdrive works just fine. I find it hard to believe I’ve been driving around with only a pint and a half in my gearbox for awhile. Can anyone solve this riddle for me? If so I would probably be somewhat relieved. I’m hoping I haven’t damaged anything, and the drive home from the mechanic went just fine, the only difference I’ve noticed is a slightly smoother gear change. Any & all advice would certainly be appreciated. Thanks
Mel R.
Others will respond, but this is something you will want to keep an eye on to make sure you do not have a serious leak. Do you see evidence of leaking anywhere under the car?
I believe that filling the gearbox and differential until they begin to overflow is the correct level.
Is this a car you drive a lot or is it sit for long periods?
Gerard
I drive the car once a week. I put about 1500 to 2000 miles a year on the car. I do not see any evidence of leaking under the car. However, I do not think the gearbox oil level was checked on my previous two oil changes, as far as I know. The mechanic said it is normal for the gearbox oil level to fall over time due to the heat generated by engine & gearbox operations, more than the differential…BTW, differential oil level was full.
Again, my concerns are as follows: 1) If the mechanic’s assistant, as he claims, added nearly three pints to a system which, according to the factory owners manual, takes just under five pints, then my oil level was down below 50%. But, the manual also says that if the oil level is allowed to drop too low, the proper operation of the overdrive could be affected. Fortunately,the overdrive engages and disengages as it should. The manual also makes a comment that the best time to change the oil would be after a long run, when oil is hot, also with a vague reference of a sizable quantity of the oil settling in the overdrive unit. 2) Since my overdrive engages and disengages as it should, and, it is hydraulically powered, is it possible the oil level was not as low as he thought, perhaps needing only 1 and a half pints added instead of three. The oil was added from a large barrel with a long hose attached. Next to the hose was some sort of guage which shows the amount added. Could the guage be inaccurate?
When I drove the 25 miles home from the mechanic’s shop, I noticed the gear changes seemed a bit smoother, which I would think is a good thing. My big concern is whether the gearbox suffered any irreparable damage from having run for a while with an insufficient oil level. I’m hoping that would not be the case, obviously, and am hoping since it is running as it should, that the problem was caught in time. I do hope, as Gerard noted, that ‘others will respond’, as at this point I am, unnecessarily, I hope, more than a bit concerned. Thanks.
Mel R.
Gearboxes/OD do leak. Try putting a cardboard under the car to catch the cat marking its spot.
Good to see Paul back as his information/knowledge is very valuable.
It might be possible that the young assistant was having math problems and WAY over estimated the amount he actually added.
You might try completely draining the system at home with a cheesecloth and a colander to see if there are any particulates in the oil. Measure the amount that has come out. You can use a suction gun with a flex hose to add NEW fluid.
You could then measure exactly how much came out and even go as far as to add what some swear by which is Redline 90 weight oil.
I know that Jaguars require constant periodic maintenance and this was their death as many owners neglected the small stuff and the engines failed. Small stuff like filing the carbs with 20 weight 3in1 oil, radiators, brake fluid removal, diffs, transmissions, etc All fun tidbits to keep our cats running smoothly.
Do you have one of the home style scissors lifts. I am so happy with our recent purchase as I can access so many things under the car now. Bought my wife a wheeled creeper so she can wheel about under the car. She has 20-50 in her blood now!!!
Gerard
Gerard
Thank you, Gerard. Unfortunately, I keep the car in a small rented garage space which would not leave much room for the scissor lift. Your suggestion that the mechanic’s assistant might be mathematically challenged does bring me some relief. As I said before, I cannot imagine if the gearbox was low by more than 50% that the overdrive operation would not have been affected. I know these cars do require periodic maintenance which makes a huge difference. I’ve been good about changing & bleeding brakes and clutch systems, checking brake linings, and, yesterday, in fact, having all the radiator hoses replaced followed by a refill with new coolant, then a complete oil and filter change. Unfortunately, the gearbox check ‘slipped’ by me the last few years. I keep cardboard under the car , there does not appear to be an oil stain under the gearbox. Once again, my final question: if the overdrive was never operating improperly, and the topping up of the gearbox with new Shell gear oil( remember this car is a later all synchro which uses 90 weight) , made the 25 mile drive home gear changes from the shop just a bit smoother, can I safely assume no lasting damage to the gearbox has taken place ? I checked underneath the car again this morning. No leaks. Please advise, encouraging news might lower my current blood pressure reading significantly. Thanks
Mel R.
Mel,
I don’t think your OD would have operated consistently with only 50% fill. In my experienc they start dropping in and out before the oil gets that low.
That’s what I hoped to hear. Thank you Andrew
With my 3.8S full synchro box and compact overdrive it does drip a bit My problem area is the paper gasket between the gearbox and the OD. At the very bottom (where the oil sits most of the time) the circular mating surface is flattened out at the bottom making the sealing surface for the gasket quite small. I loose maybe a third of a cup in a year’s time.
John Quilter
Eugene, Oregon
Thank you John. I called the mechanic and asked him if he’s certain his assistant could have added three pints to my gearbox when the whole system only takes 4 and 3/4 pints. He then said he thought that’s what his assistant said he did, but, like us, he was also skeptical the overdrive and gearbox had been running well with only a pint in them! He said he ‘thought’ one stroke of the pump handle on the barrel of gear oil would equal one whole pint, but then said he’d check with his father to make sure. He also said that since the barrel may have been close to empty and the hose from the barrel has a substantial length, perhaps the first few strokes on the pump merely pushed air out of the hose until gear oil emerged. Now he also thinks maybe only a pint and a half at most may have actually been added to the gearbox. There are no leaks under the car, and the only difference between the operation of the gearbox before and after the visit to the mechanic the other day (25 miles each way) is, before it ran well, now gears shift even a bit more smoothly than before. I’ve decided to stop worrying about it any more & just enjoy driving the car. Thanks to all for your advice.
Mel R.