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Synthetic Oil Escape

RAC68

Darth Vader
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Hi All,

As a proponent in the use of Synthetics within a number of Healey major components (ie. Mobil 1 15W50 engine oil, etc.), I must rescind my support for Red Line MTL/90 within the OD/Transmission. For the last 4 or 5 years, I have used Red Line synthetic MTL and have found it providing smoother shifts and resonsive OD activation, however, its tendensy to find an escape path from the transmission has proven a far too risky issue having consequential damage potential.

I am not talking drips on the garage floor but major problems that have caused more then just concern. Not long after switching from 30W-non detergent motor oil (used since new with no problems) to Red Line, I found my OD stopped operating. After initially checking, I found the level of fluid had dropped by 1/2 on the dip stick.

So, since there was no major puddle of MTL on the floor under the car, where did it go? Investigation showed that the fluid had escaped past the "O" ring used to seal the cross-OD actuation rod and filled the solenoid mounting enclosure causing the solenoid piston to hydraulically lock (BJ8s have a cover enclosing the solenoid mount).

Removing the fluid from the enclosure, cleaning the solenoid and piston, and maintaining the Red Line MTL to a level just below the shaft, the original solenoid again performed perfectly and all was well for the next 2 or 3 years of use.

Being confident with no leakage or issues for a significant (my perception) period, earlier this year I decided to fill the OD/Transmission to the FULL mark. Big mistake. Yesterday, taking the car for a short drive after an extended period of inactivity (Weather permitting, I try to drive my Healey at least once/month), all seemed well. At the STOP sign at the end of the road however, I noticed the clutch slipping but continued for a few miles more. When finally arriving back at my home, the clutch slip had grown quite concerning and I found the level of Red Line MTL at 1/2 full.

The actuation of the clutch remained quite good and, although the clutch/pressure-plate/throw-out bearing were renewed quite a while ago, there was no previous indication of ware or issues. At present, based upon the fluid loss, I expect to find that the Red Line has escaped through the front bearing seal and may have collected on the bottom of the bell housing and may have saturated a portion of the clutch. During the drive, this clutch saturated fluid may have been distributed over the pressure plate and resulted in further extending clutch slippage.

Although I am hopping the fluid will burn off, the possibility of not needing to pull the transmission and replace the clutch is, as I see it, 50/50. However, one thing is certain, I will be replacing the Red Line MTL and going back to 30W NON-Detergent motor oil.

Any Thoughts or Suggestions?

Ray(64BJ8P1)
 
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Bob_Spidell

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Re: Synthetic Excape

"Any Thoughts or Suggestions?"

Many thoughts, for sure, as I was about to replace 20W-50 'break-in' oil in my gearbox/OD with MT-90 (I loaded the mineral oil first, as I'd used grease to hold the bearing shims in place during assembly and wanted to flush it out before installing ($$$) Redline). I have used MT-90 for many years/miles--I'm guessing about 10/50K--with some leakage (about, maybe, a pint over 5,000 miles). I can attest that the MT does provide smoother shifting and somewhat quicker OD engagement than engine oil, though that is now a non-issue with an uprated accumulator installed.

When I had my engine rebuilt and the gearbox on the bench last year for inspection I overfilled the gearbox when I installed it, with MT-90, by about a half-quart, and it peed oil from the front seal and out the drain hole in the bellhousing. I drained the excess and all was well until I pulled the gearbox/OD last winter to address a jumping-out-of-fourth problem. Not surprisingly, the inside of the bellhousing was smeared with oil, but the clutch assembly was bone dry--not at all what I expected--so I'm not convinced oil leaking out of the front seal is the problem with your clutch. The drain hole, assuming it's not plugged, should vacate quite a bit of oil before it allows it on the cover plate, and even if it gets on the cover plate I suspect it gets thrown to the inside of the bellhousing, where it could drip on the clutch, but I didn't see that. How many miles on your clutch? Unless you do mostly 'city' driving say, in San Francisco, you should get over 100K miles on a clutch. My guess is the clutch starting to slip is a coincidence.

The O-ring sealing the activation shaft on the solenoid side is probably toast, but I'd suspect the one on the other side would be just as worn, and you'd get leakage from it as well, but apparently that's not happening. Earlier cars did not have a cover on the solenoid operating mechanism; I presumed they added it due to contamination of the solenoid from dirt and road grime. David Nock and a couple of his mechanics mated the OD to the gearbox for me, after I'd tried for several days with no luck, and one of his guys told me they don't bother putting the gasket or the rubber boot on the solenoid (it appeared to me the boot supplied with the solenoid wasn't going to fit no matter what). Makes me wonder why the box that covers the mechanism doesn't have a hole in the bottom for drainage--with a cotter in it?--but I guess that would defeat the purpose of the cover. FWIW, David advocates MTL in the gearboxes/ODs they rebuild and service--I asked him why and he said 'MT-90 is too thick'--but I noticed his people smeared Permatex Aviation Form-A-Gasket quite liberally on the parts they assembled. Side note: there is a hole on bellhousing where the shift lever gets mounted--I think it's there to allow installation/removal of the pin that anchors the shift fork to its shaft--and I covered it with a plastic plug as dust could enter there.

I always got some seepage from the gearbox/OD with either lubricant; it always leaked a little at the big brass plug on the OD, and the most 'notorious' point for leakage is at the brake ring in the OD, as it's usually installed without a gasket. I'm getting ready to embark on my annual long road trip and, given your experience, I'm seriously considering not replacing the mineral oil with the synthetic right before I go.

Unfortunately, Ray, I think you have to pull the gearbox/OD to replace the clutch and, while it's out, you'd probably want to at least replace the O-rings on the actuator shaft. It's universally acknowledged that synthetic oils leak more than mineral oils--the whole point of the syns is that they're 'slipperyer'--but going from non-leaking to gushing with MT-90 is excessive; I suspect you'll find some other issues at play as well.
 
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Bustren

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Re: Synthetic Excape

Hi
I would check the breather to ensure that pressure is not built up inside the gearbox as temperature raise to operating level.
I have been using Readline MTL for many years without any significant leakage. Readline MTL is pretty close to SAE30 viscosity, but probably on the lower side.
Important is to seal the bolts for the clutch housing to gearbox as the oil can leak through the threads, the bolts "goes inside" the gearbox.
brg Lars
 

Bob_Spidell

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Re: Synthetic Excape

Hi
I would check the breather to ensure that pressure is not built up inside the gearbox as temperature raise to operating level.
I have been using Readline MTL for many years without any significant leakage. Readline MTL is pretty close to SAE30 viscosity, but probably on the lower side.
Important is to seal the bolts for the clutch housing to gearbox as the oil can leak through the threads, the bolts "goes inside" the gearbox.
brg Lars

Good points, Lars. When I reinstalled my gearbox/OD--the first time--I put fresh copper washers under grade 8 flat washers under threadlocked bolts. When I pulled the gearbox/OD there was no evidence of any leaking around the bolts when I pulled it again 6K miles later.
 
OP
RAC68

RAC68

Darth Vader
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Re: Synthetic Excape

Hi Bob/Lars and thank you for your thoughts and advice.

I believe I found the lions share of missing Red Line MTL. Since I added the Red Line to the full mark about 2 months ago and took a 10 mile drive immediately after with no level change or any transmission/OD issues, I felt quite confident all was good. I had kept a thick folded carboard wardrobe box under the car for the past 2 years until only a few days prior when I replaced it, not noticing that much lube moisture. However, on closer examination, the cardboard seemed to have a greater amount of fluid absorbed within and could be a major portion of what seemed lost.

Although no were near 100k miles of use is on the clutch, the setup has performed responsively and without any slippage as I am hypersensitive when it comes to how my Healey performs and would definitely noticed any issues … especially clutch slippage. Today I took the car for a quick mile drive down the road and back in order to turn the car around and see if the clutch was still slipping. Although cloudy and colder (62 deg. apposed 90 deg. the other day) and a much too short drive to really draw conclusions from, the clutch did not appear to slip. Although this conclusion could change if driven much farther, it seems a hopeful indication that I might not need to pull the transmission and change the clutch.

Having aged physically quite a bit since the last time I pulled the trans, I am not only not looking forward to pulling the trans but wonder if I still have the strength. However, if I need to, when its out, I will go through every opening within the trans/OD housing and find a way to seal it. That would include bolt threads (as Lars mentioned), bearings, or shaft "O" rings. Although this may not secure MTL within the confines of the trans/OD, I would bet, as you have mentioned, others have done this and could extend suggestions.

Again, thanks for your suggestions and all the best,
Ray(64BJ9P1)
 

Bob_Spidell

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Re: Synthetic Excape

I first started experiencing clutch slippage on a long road trip three years ago (once, on a 4K trip). Before the trip two years ago, I performed the 'standard' clutch test: Put the gearbox in first, and let out the clutch at off-idle and see if the engine stalls; it did, so I took the trip two years ago and the clutch started slipping more regularly. I first noticed slippage when shifting pulling an uphill grade, then periodically over the 4K+ trip (but we made it home by 'easing it in' when it started to slip). What I'm saying is, it's possible you won't notice any slippage on a short, non-challenging drive but might when things heat up. Do you have any steep hills in your area where you can really challenge the clutch? Of course, if you have to pull the gearbox/OD you'll probably want to install a new clutch on principle.

I'm lucky; my dad has a guy working for him that's as strong as an ox. When we went to install the gearbox two years ago I was in the car getting the slave out of the way, etc. and the gearbox was on the bench. I told Matt I was ready to install the gearbox, assuming he and I would lift it into the car, but he had already picked it up and was carrying it like it was baby.
 

Michael Oritt

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Re: Synthetic Excape

I use Redline MT90 in my Healey as well as the MG transmissions in both my Elvas. All of these (Toyota 5-speed in the 100, MGA in the MK IV sports racer and MGB in the Courier) are non-OD boxes so I cannot comment on leakage past OD seals. However I have never experienced any leakage past input shaft seals and onto the clutch such as Ray described and I wonder what his experience would have been with non-synthetic oil.

As to the Redline's performance I cannot comment on its improving shifting on the Healey as the Toyota transmission provides such superior performance that it would probably be just fine with any suitable oil, dino or synthetic. However, I can definitely say that the Redline provided better shifting on the two MG boxes and whereas I could often "beat the synchro" on fast shifts (up or down) with 30w non-syn oil, with the MT90I can shift as fast as I am able and not experience the small "crunch" that the dino would often produce.
 
Last edited:
OP
RAC68

RAC68

Darth Vader
Offline
Hi All,

To follow up on the escape of the Red Line MTL and resulting clutch slippage, I spend the last few days draining the Red Line MTL synthetic and replaced it with a full measure of 30W Non-detergent oil hopefully to eliminate any further leakage (used 30W non-detergent from new to about 5 years ago when I installed the Red Line MTL and never had transmission/OD lube leakage) or clutch slippage. Although the Red Line provided smoother shifting with quick OD responsiveness, leaking from the confines of the transmission/OD became a growing issue and, sealing every potential escape path, far more then the original seals could handle. Although it is possible to improve trans/OD seals and address most, if not all, possible escape paths, It would require pulling the transmission and a job I would only consider if I need to change the clutch disk.

Comparing the Red Line MTL Synthetic to the 30W non-detergent mineral oil, I noted that the viscosity of the 30W seemed greater although the MTL is supposed to be slightly lighter on the gear oil scale. During a brisk 45 minute drive through the hills where I live, I noticed no apparent clutch slippage … which made me quite happy. However, this is only an initial indicator and I would feel more confident after a few more drives without slippage. Shifting seemed a little tighter/slower with the 30W oil but OD activated and deactivated briskly (possibly higher pressure due to the seemingly thicker oil).

Bob, you may have been correct and only a small amount of Red Line may have gotten onto the clutch disk or pressure plate. However, I won't be able to verify unless I pull the trans and I am hopping not to have to do this.

At this point, I am a Happy Healey owner and hope I stay that way,
Ray(64BJ8P1)
 
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