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Transmission advice.

8K views 79 replies 13 participants last post by  dave3d 
#1 ·
I was not sure if I needed to start a new thread ( I posted on TheoR thread from 8/2016, who had the exact manifestation as I did). So here it goes.

I had a VERY similar problem to TheoR on my way to the airport (go figure, right?), needless to say I missed my flight and got towed to my repair shop, my mechanic checked the transmission fluid level (yes I have an earlier version with a dipstick) then drove the car and confirmed the disconnect between the purring engine and the wheels, so he consulted with a transmission "specialist" and the estimate to overhaul the transmission came to $4K.

I decided to bring the car home and ponder (1996, P38 4.0 with 220K on the odometer) so I brought a quart of transmission fluid with me just in case ( after reading an earlier post here regarding the proper way to check the fluid).
And upon checking the dipstick with the engine running, the cold level was not readable, so I poured the one quart and drove home (12 miles) without a glitch.

Now this is my dilemma; what is next? accept that I solved the mystery and move on? will this happen again and I will be left stranded? have the transmission looked at? check for leaks? is there a way to do a "preventative maintenance" without an overhaul?

Any input is appreciated.

Rod


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#2 ·
Your 4.0 will have the ZFHP22EH gearbox. A quick check on the Ashcrofts website (a well regarded L/R transmission specialist in the UK) shows an exchange unit is £725 to give you a price comparison.


Your quote of $4K is well over the top even with fitting costs. I would doubt that the gearbox is completely wrecked due to just a low fluid level.

I would crawl underneath and check for leaks first. You may have got away with it if the level has not been checked for years. Nearly all p38's drip from somewhere so it may have been gradual.

If all is good I would double check the level again and do a few test drives, checking underneath regularly. If the gearbox works as it should and there are no leaks then that is enough.

If no maintenance has been done on the gearbox for years, change the filter and put fresh Dexron III fluid in. Do your transfer box as well with the same spec fluid.
 
#4 ·
In my case, the torque converter spline was completely worn out so topping up the ATF didn't solve my issue. As such, I bought a new torque converter for around $150 and did the replacement. It took me a few days to fix the problem myself, but saved quite a bit on my repair bill. There's no way it should cost $4K. However, getting a quote like that is pretty typical. The transmission work that I did was the second time my P38 got a transmission job. The first time was done by a shop, and I paid something close to $5k for the repair.

Going back to your issue, if topping off ATF solved the problem, chances are you just had a slow leak somewhere and run low enough on the ATF to no longer be able to operate the oil pump properly to propel the torque converter. You might have lucked out and may not have any issue after the top off. However, pretty certain you have a leak somewhere, so go through all the area ATF flows to pinpoint the leak.

Telltale sign if you have done any further damage to your transmission is whether you had any gearbox fault come up on your instrument panel. There is a temperature sensor attached to the transmission oil cooler that triggers the fault if the ATF doesn't cool down sufficiently. I saw the warning couple of times, but didn't do anything to address the warning as the fault was not coming up on a constant basis.
 
#6 ·
In my case, the torque converter spline was completely worn out so topping up the ATF didn't solve my issue. As such, I bought a new torque converter for around $150 and did the replacement. It took me a few days to fix the problem myself, but saved quite a bit on my repair bill. There's no way it should cost $4K. However, getting a quote like that is pretty typical. The transmission work that I did was the second time my P38 got a transmission job. The first time was done by a shop, and I paid something close to $5k for the repair.

Going back to your issue, if topping off ATF solved the problem, chances are you just had a slow leak somewhere and run low enough on the ATF to no longer be able to operate the oil pump properly to propel the torque converter. You might have lucked out and may not have any issue after the top off. However, pretty certain you have a leak somewhere, so go through all the area ATF flows to pinpoint the leak.

Telltale sign if you have done any further damage to your transmission is whether you had any gearbox fault come up on your instrument panel. There is a temperature sensor attached to the transmission oil cooler that triggers the fault if the ATF doesn't cool down sufficiently. I saw the warning couple of times, but didn't do anything to address the warning as the fault was not coming up on a constant basis.
Thank you TheoR and dave3d for your input, I just finished inspecting the undercarriage; no "major" leaks that I could see, but admittedly it is hard to tell since I DO have chronic oil leaks from the oil pan and the engine block, but the ATF level stayed where I left it after the top-off.

I just ordered the kit including the filter and gasket, and I might as well do the transfer case oil change while at it.

I am counting my blessing with this car, I had a prior close call with the transmission about 7 years ago; while my wife and I were on our way home from a skiing vacation in Colorado (with a car full of kids and dogs) and I was approaching a small town (El Norte if my memory serves me well) I noticed an erratic RPM then a loss of power, at the same time my wife smelled a "strange smell', so I pulled over and found the engine compartment soaked with oily substance, luckily we were less than a couple of blocks from the town center, where the only repair shop was about to close (Friday evening) for the weekend, I pleaded with the mechanic/owner to take a quick look, he stated that he smelled a burning transmission right away and nothing could be done till Monday the earliest (that is if the needed parts were available from Denver). but upon my insistence he took a look and found a ruptured hose in the engine compartment that leaked all the ATF.

So without any guarantee that the car was going to run again, he replaced the hose, filled the fluid and.... we made it home that night ( the smell was nasty the whole way home and for the next few weeks although he pressure sprayed the engine compartment when he was done).
 
#5 ·
As noted, if topping off the ATF resulted in the problem being solved, and the transmission now works, then that might be problem solved.

Where did the ATF go? A few things to check:

Oil leaks around the pan, obvious enough.
Check the oil cooler hoses from the transmission to the oil cooler for leaks at the joints. These are under pressure so even a small leak will mount up over a short time.
Check the oil cooler itself for weeps or a leak. Once again, it is under pressure whenever the engine is running. To that end, start the car, cycle the gears and then check with the engine running.
Have a look at the little inspection plate on the bottom of the bell housing. Pull out a bolt and see if fluid comes out. If so then there might be a leak on the input shaft.

Worthwhile getting a service kit, pretty cheap, and 11 litres of ATF and service the transmission. An easy, if a little messy job.
 
#10 ·
My car is ex police and one of the things they liked about the P38 was that you could slam it into reverse no matter how fast you were going to stop the car almost dead. The gearbox knew they were still travelling forwards so rather than going into reverse, it just locked up until travelling slow enough to select it. So waiting until you have stopped isn't that important.
 
#12 ·
nosync, if you have overheated the box in the past, the ATF fluid must be changed. Run some off and have a look at it in a jar. It should be a dark red colour. If it is black it has degraded and will cause damage. Up to 200 deg F is normal running temp. Above 250 deg F change after 10K miles. Above 300 deg F too late damage occurs. I put a gauge on mine to keep an eye the temp.
 
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#13 ·
FYI, my source of leak was the transmission oil cooler. Even under operation, ATF wasn't spewing out of it or oozing out that I could detect visually. The leak, however, was sufficient enough and going on for long enough to layer the overall surface of the transmission oil cooler in ATF. The leaking ATF had the effect of being an attractant of dust on the surface of the transmission oil cooler, completely caking the surface in dust as a result.

I imagine your current leak may be similar to what I experienced, unlike your first time, in that the leak may be very small. Only way to detect the origin of the leak may be to thoroughly clean the surface area around where ATF flows, drive around a bit, then look for surface tainted by ATF.
 
#14 · (Edited)
Thank you dave3d and TheoR for the input, My plan is to service the transmission/transfer case anyway ( that will give me a chance to check the ATF color) de-grease the undercarriage and the engine compartment, drive the car while checking for leaks often and go from there ( I wonder if a UV light lamp would help?)
 
#15 ·
I have only seen a UV light used for detecting aircon leaks when a special UV dye is added. Don't think it would work with ATF fluid.
Wear yellow UV goggles if you are messing about with UV.
 
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#16 ·
I have a 97' P38 with 230k (Previous maintenance Unknown) that wasn't able to maintain a constant speed above 50 MPH without constantly kicking down a gear. I finally changed the Trans Filter, Fluid and added a stronger magnet inside. The issue cleared up. Then a Flexplate bolt backed out for some reason and took out the RELUCTOR Ring, and stopped the engine. I decided I was going to get the transmission rebuilt (In the shop for this now). For $2500 They are rebuilding the Transmission, Changed Rear Main Seal, Oil Pan Gasket and installing the New Flexplate (I bought from Island 4x4 for $500) And an upgraded Flexplate Drive Plate (From Ashcroft for $100). ALL in for about $3100... I am going to keep it for awhile so it's worth it to me...
282186
 
#20 ·
Happy thanksgiving first of all.

As mentioned earlier I did the service, but when it came to filling the ATF: it was a challenge.

One of the members on this forum said 11 liters ( which I thought was excessive) I looked up my 1996 4.0SE specifications: it said 9.7 liters, but even then I could not fill that much into the transmission case.

So that begs the question: are the 2 liters for the torque converter / transfer case part of that 9.7 liters? Even then I could not put the balance of 7.7 into the transmission case ( it took about 6 liters to be overfilled and had to drain a liter and a half back).

Any input?


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#23 ·
yes - check the level with engine running, cold. In practice that mean get the level as right as poss with the engine running (even if warm), let the oil cool off/ contract, and then level off whilst running & cold - remembering to cycle through all the gears too. Your gearbox could easily have been over/ under-filled in the first place, so I wouldn't be unduly worried if the refill is +/- 1L. I too have been through the fill it up, drop a bit out cycle !! When you're at the bottom of the stick it really only takes a small volume to get to the right level, as the stick is near horizontal at the bottom as it bends down the tube and into the gearbox.
 
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#25 ·
Because the torque converter is inside the bellhousing at the front of the gearbox and the transfer case is a completely separate unit bolted to the back on the gearbox. Just because they are both sometimes referred to as TC doesn't mean they are the same thing, TC also is used when talking about Traction Control......
 
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#26 ·
An update and a question;

ATF level is staying where it should be, a drop or two under the car overnight (mix of oil and negligible amount of ATF, so I think my incident took a few years for the level to drop enough to cause the problem).

Now to the question; the shifting is kind of abrupt and occasionally with a clunk, especially when the car is cold, any input? is that a bad sign?
 
#27 ·
If the shifting pattern didn't exist before you replaced the ATF, something must have happened during the fluid change. First question that I have is, did you make certain you used the right ATF fluid? Not all ATF is the same, and you must use the specific ATF designated for the particular transmission. There is a separate thread about a case where a transmission started to exhibit a whirring/whining sound after accidentally filling the transmission with a wrong spec Dexron, a Dexron 6.

Also, as previously noted, transmission must be filled while the engine is running, but when the ATF fluid is cold. Did you diligently follow the procedure? ATF fluid expands when heated, so if you took too much time to fill the transmission, you may have to wait until the fluid is cold enough and repeat the process.
 
#28 ·
Thank you for the pointers TheoR.

I used Dexron III which is what the forum called for,
I did not know that I needed the engine running while filling the transmission fluid so I did not, but I have been checking the level before every drive (I have the dipstick version) so even if there was a filling error on day one; I should have seen it by now, no?


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#29 ·
nosync - check out post 23.... But to your point above if you've only been checking the level with engine off, then no, you wouldn't have spotted the under-fill - your box needs filling !!
 
#30 ·
nosync - check out post 23.... But to your point above if you've only been checking the level with engine off, then no, you wouldn't have spotted the under-fill - your box needs filling !!
Thank you romanrob, but I think there is a misunderstanding here: yes I followed post #23 already and the level is between the two dots, I was referring to the post prior to yours: “filling” with ATF with the engine running.


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#32 ·
Looks like you've used the right type of Dex 3 called out for.

I have a Thor, and thus I don't have a dip stick to check the ATF level. However, shouldn't the filling procedure as well as the checking procedure (other than the dip stick part) be the same? As in, have the engine running and going through all the gears while the ATF is still relatively cold?
 
#33 ·
It is the same when levelling, but not filling ie you wouldn't run the engine with an empty trans doing the initial fill, right?
It's hair splitting, but some folks will take things literally, or think there's some magic in having filled and run from start to finish.
 
#35 ·
Effectively the procedures are the same for both the V8 autos, yes, but that wasn't where the initial confusion came from.
 
#36 ·
Theo, there is one big difference in filling the autobox for GEMS and Thor, apart from ease of access. You can fill the older ones via the dipstick tube with the correctish amount, then start the engine, go through the gears and check on the dipstick. On the Thor, you need to have the engine running or you'll never get enough oil in because the filler is lower than the oil level with engine not running and it just pours out again.
 
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#37 ·
So I took my P38 for the longest drive yet, at speeds up to 85 mph ( exceeding 95 for a brief period), all went well for the first 150 mile.
And as I was approaching my exit, I noticed that it was “hunting” for the right gear, then I got the “gearbox fault” message on the display in the dashboard, and the car kept itself in 3’d gear for the rest of the trip (40 miles) regardless of the speed (taking off in 3’d from a stand still at the traffic light was not fun) and the gear symbol (D) disappeared from the display.

What is next?



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