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| 1988 Fiero Formula - auto transmission fluid leak (Page 1/4) |
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br1anstorm
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JUN 23, 01:37 PM
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I have a 1988 Fiero Formula with - of course - auto transmission. I understand it's the Muncie TH125 3-speed with torque converter.
Today it suffered a serious transmission-fluid leak. I had noticed a slight dribble-trail on the road as I parked the car on an 10 mile trip to the shops. I turned round and got the car home.... just! (It drove, but for the last mile or so it was clearly not shifting normally). I don't think it's a good idea to try to move it any more under its own power.
Now I'm trying to do some basic diagnostics.
I haven't yet been able to lift the car up on ramps to look underneath properly. But the leak appears to be at the front: somewhere just inside the front left wheel arch (ie roughly under the driver's footwell). It's definitely transmission fluid, which is still red, not brown or smelling burnt.
I have the service manual. But I cannot find a schematic diagram or picture there or anywhere online which shows where the transmission fluid lines run. I'm assuming that there are two pipes which run from the auto transmission forward to a cooler somewhere in or beside the radiator at the front of the car, which take hot fluid forward and cooled fluid back to the actual transmission. So my best guess is that there is a leak in a seal, joint or pipe somewhere in one or other of those lines.
Q.1 - can anybody advise where I might see an image which shows where the pipes are routed and where any joints or seals are?
Q.2 - if I re-fill the transmission with fluid .... even though there is a significant leak .... will that enable me to drive the car - gently and without causing damage! - a mile or so to the workshop? [if the answer to that question is no, the alternative is presumably to get a tow truck, or trailer the car to the workshop....]
Q.3 - what is the total capacity of the transmission system - ie how many litres of fluid would I need in order to refill the transmission to enable the car to be driven a short distance?
Q.4 - is Dexron II the correct (and only) fluid to use, or if not what other brand/specification would be suitable?
Any other advice, warnings or comments would be welcome.....![This message has been edited by br1anstorm (edited 06-23-2023).]
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br1anstorm
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JUN 25, 06:21 PM
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Well .... as no-one has commented on my original post, I might as well provide an update.....
I have at least answered Question 1. I've got the car up on axle stands and had a look underneath, and the auto transmission fluid cooler lines are pretty clearly visible for most of their length. Most if not all the fluid has leaked out, although I cannot see exactly where the hole(s) might be.
No surprise that one or more of the pipes developed a leak. Mild steel pipes, with a - presumably - mild steel coiled "protection" wrapped around them. Might give some insurance against damage from a hit by a small stone. But a guaranteed invitation to corrosion and failure, made worse by the fact that the coiled covering makes it impossible to see or check for any impending leaks. Surely not one of the best engineering and design decisions made by GM?
The obvious solution is to have replacement lines made up from 'Cunifer '(a copper/nickel/iron mix used extensively in the industry for brake and hydraulic lines). This is malleable so can be shaped more easily than stainless steel, but wont corrode. So that's what I'll be asking my workshop (who have all the tools) to do.
However - I'd still quite like comments on the other questions in my original post.....[This message has been edited by br1anstorm (edited 06-25-2023).]
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shemdogg
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JUN 25, 08:27 PM
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Fill it up w trans fluid and it should mark its spot where its leaking. It will shift fine w the right amount of fluid in it, but if the leaks bad enough it may not make it the mile to the shop. The dipstick will tell you when its full, fiero store sells the lines. Dex2 or better works.
https://www.fierostore.com/...0%20%20%20%20%201988
shem
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br1anstorm
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JUN 26, 09:34 AM
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| quote | Originally posted by shemdogg:
..... It will shift fine w the right amount of fluid in it, but if the leaks bad enough it may not make it the mile to the shop.....
shem |
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Thanks shem - it's very helpful to have advice. I'd thought about refilling just to see exactly where the leak is. One problem is that it looks as if the leaking fluid runs along and around the coiled stuff that covers the actual pipes, which makes it hard to pinpoint the leak, never mind trying a temporary seal!
But your comment quoted above is the one that worries me. No problem about filling up with fluid, but I don't want to wreck the auto transmission in a mile-long trip across town....
Looks as if Dexron 2 or Dexron 3 (or any Dexron - it seems they are now up to version 6) will do, as they are said to be "backwards compatible".
Fingers crossed that I can get it to the workshop....
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theogre
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JUN 26, 09:31 PM
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If hose is bad or fix hard line w/ hose...
It must be "Trans fluid" rated.
Hot Trans Fluid will "eat" other hose types and often soon even tho has 0 pressure for most GM vehicles.
Find at many stores selling aftermarket coolers. ------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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br1anstorm
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JUN 27, 11:18 AM
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Thanks, ogre, for latest advice. The main problem is that I'm in UK, not the USA.... and there are no stores over here that would stock aftermarket cooler lines for a car (Fiero) which is almost unknown over here!
As the original lines on my car are now rusted and leaky I have no option but to replace them. I'm not that keen on a 'quick and dirty' fix such as cutting out the section where the leak is and fitting a flexible tube with compression fittings. The lines are likely sooner or later to leak somewhere else.
One option is to order new preformed stainless steel pipes from the US. So far I have found The Fiero Store and a company called InlineTube.com as possible sources. But the combination of international shipping plus UK customs and import duty makes the cost exorbitant (and although lightweight, the preformed lines are long and fragile, so vulnerable to damage) .
I'm wondering if an alternative would be to get flexible, braided, transmission hose, something like these items listed on eBay
[url=https://www.ebay.com/itm/404031499795][/url]
But to order them online - or even perhaps to see if a firm in UK could make them up for me - I would need to know the hose diameter, the exact length of each line, and the fittings at each end. Can anyone advise me on those essential details?[This message has been edited by br1anstorm (edited 06-29-2023).]
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theogre
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JUN 27, 01:08 PM
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Again, trans oil cooler lines see near 0 PSI...
Anything for hard lines will replace the OE lines.
Copper tube from normal plumbing or thicker for building AC can work. Many Benders will handle both types, others only for "cheap" soft copper for water.
Can get steel lines but needs benders for them.
SS, copper and others can have "rust" problems where clamps and car hits them.
To prevent that... get heat shrink tube, slid to affective spot, then shrink it.
Example: Fuel lines and Filter under many Fiero can "rust out" OE and SS return where it goes thru clamp holding the filter.
After fixing the problem I did same for that section so line can't touch steel clamp or SS body of the Filter.
Did similar to heater lines next to fuel tank because OE plastic layer on return worn off and cause a rust hole in Aluminium tube.
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br1anstorm
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JUN 28, 05:29 AM
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Thanks again - I agree that it makes sense to use heat shrink tube (or indeed rubber from bicycle inner tube!) to insulate and protect water, fuel and brake lines from corrosion where they are held by clamps to the car body. I have done this already on the water pipes on my car,
But that wasn't the question I asked.
I'm interested to know
(a) whether flexible braided auto trans cooler hoses (as shown in the link I posted previously) - can be fitted to replace the original hard lines? Has anyone done this?
(b) if so, what length of hose(s) is needed, what diameter, and what connector fittings at each end? It's hard to measure the length of the original lines when they are still fitted to the car.
Answers to those questions would be appreciated.
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shemdogg
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JUN 28, 09:19 AM
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That ebay kit will get you by, you may need a compression fitting to 6an where it joins the line. Another option is just to buy the tubing, flare kit, and a bender and make it yourself. You can reuse the threaded fittings on the new lines. Or find a tubing shop you could take yours to and they make ones to match.
shem
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82-T/A [At Work]
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JUN 28, 10:31 AM
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| quote | Originally posted by br1anstorm:
Thanks again - I agree that it makes sense to use heat shrink tube (or indeed rubber from bicycle inner tube!) to insulate and protect water, fuel and brake lines from corrosion where they are held by clamps to the car body. I have done this already on the water pipes on my car,
But that wasn't the question I asked.
I'm interested to know
(a) whether flexible braided auto trans cooler hoses (as shown in the link I posted previously) - can be fitted to replace the original hard lines? Has anyone done this?
(b) if so, what length of hose(s) is needed, what diameter, and what connector fittings at each end? It's hard to measure the length of the original lines when they are still fitted to the car.
Answers to those questions would be appreciated. |
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Maybe not the answer you're looking for... but the Fiero Store here in the United States sells COMPLETE replacement lines made of stainless steel for your transmission cooler. Also new fuel lines if you're so inclined as well.
84-88 Auto Tranny Cooler Lines - $149
https://www.fierostore.com/...0%20%20%20%20%201988
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