1998 convertible fluid leak

339 Views 24 Replies 5 Participants Last post by Spade, 4 d ago

Spade

Discussion Starter · 1 mo ago

Hello. I have a 1998 Firebird convertible which needs some repair. There is a tiny leak from the hydraulic system somewhere "upstream" from the electric motor. The fluid seems to be dripping inside the wheel well and falling to the ground right at the lower corner of the quarter panel, behind the wheel. There are no obvious leaks in the trunk area around the motor/reservoir.

Is there a "most likely" cause for this leak? I'm thinking the cylinder is worn out and should be replaced, but I have no prior experience with convertibles so am just guessing at this point.

If not the cylinder, what might be the next thing to check?

If I can determine the cylinder is the problem, is there a replacement set anyone can recommend?

Also, on the reservoir there are 2 molded lines. When topping off the fluid which line am I aiming for?

Finally, I've seen various online posts going back 20-odd years about the proper fluid to be used. Originally ATF, which I'm still using, but I've also seen motor oil and baby oil. Is there an "official" determination on this?

Thanks for any help or direction anyone can provide.

1 - 20 of 25 Posts

Injuneer

· #2 · 1 mo ago

The 2000 factory service manual (page 8-951) indicates the replacement hydraulic cylinders are pre-filled, and that "Recommended fluid replacement is M-H5606". I didn't check the 1998 manual. Free download here:

www.mediafire.com

MediaFire

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H5606 is hydraulic oil. I believe the "M" elevates it to MIL -spec grade:

petroleumservicecompany.com

What is MIL-H-5606?

What does it mean when an oil meets MIL-H-5606 specifications? There are different oils and lubricants for just ab...

petroleumservicecompany.com

This diagram (VIEW C) appears to indicate that any level between the two lines is acceptable.

http://shbox.com/1/conv_top_pump.jpg

GaryDoug

· #3 · 1 mo ago

Injuneer said:
The 2000 factory service manual (page 8-951) indicates the replacement hydraulic cylinders are pre-filled, and that "Recommended fluid replacement is M-H5606". I didn't check the 1998 manual. Free download here:

MediaFire

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

H5606 is hydraulic oil. I believe the "M" elevates it to MIL -spec grade:

What is MIL-H-5606?

What does it mean when an oil meets MIL-H-5606 specifications? There are different oils and lubricants for just ab...

petroleumservicecompany.com

This diagram (VIEW C) appears to indicate the any level between the two lines is acceptable.

http://shbox.com/1/conv_top_pump.jpg

Fred, your signature link does not work.

Spade

Discussion Starter · #4 · 1 mo ago

Injuneer said:
The 2000 factory service manual (page 8-951) indicates the replacement hydraulic cylinders are pre-filled, and that "Recommended fluid replacement is M-H5606". I didn't check the 1998 manual. Free download here:

MediaFire

MediaFire is a simple to use free service that lets you put all your photos, documents, music, and video in a single place so you can access them anywhere and share them everywhere.

www.mediafire.com

H5606 is hydraulic oil. I believe the "M" elevates it to MIL -spec grade:

What is MIL-H-5606?

What does it mean when an oil meets MIL-H-5606 specifications? There are different oils and lubricants for just ab...

petroleumservicecompany.com

This diagram (VIEW C) appears to indicate the any level between the two lines is acceptable.

http://shbox.com/1/conv_top_pump.jpg

Well so far I've searched the 1998 service manual for "M-H5606", "H5606", "Recommended fluid replacement", and "reservoir", and nothing turns up. If the information is in there it's hiding very well.

And thanks for that diagram. I had been filling it to between those lines but this is the first confirmation I've seen. So, one puzzle solved.

Injuneer

· #5 · 1 mo ago

I looked at the 1998 manual, in the section on replacing the cylinders it mentions the cylinders are pre-filled, but does not mention the refill fluid spec.

Looking through the various years of the manuals, there is no visible difference in the components used. I seriously doubt anything was changed over the 94-02 years of the 4th Gen convertible.

Did you check your owner's manual? My 1994 manual has nothing in the fluid specs section, but the convertible was not introduced until late in the 1994 model year.

roorancher

· #6 · 1 mo ago

Are you sure the spec is not MIL-H5606?
That's an aviation mineral based hydraulic fluid, and very common.
But what I have pictured also meets the spec, and I got it at Tractor Supply.

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Reactions: 1

ZumpTA

· #7 · 1 mo ago

roorancher said:
Are you sure the spec is not MIL-H5606?

Read post #2 again.

Reactions: 2

Injuneer

· #8 · 1 mo ago

ZumpTA said:
Read post #2 again.

There's an echo in here……..

Reactions: 1

Spade

Discussion Starter · #9 · 1 mo ago

Injuneer said:
Did you check your owner's manual? My 1994 manual has nothing in the fluid specs section, but the convertible was not introduced until late in the 1994 model year.

The 1998 manual also doesn't have anything in fluid specs section.

Spade

Discussion Starter · #10 · 1 mo ago

roorancher said:
Are you sure the spec is not MIL-H5606?
That's an aviation mineral based hydraulic fluid, and very common.
But what I have pictured also meets the spec, and I got it at Tractor Supply. View attachment 233455

I've been using ATF. I wasn't clear in my original post; I want to make sure that if I install new cylinders that the fluid isn't damaging the seals somehow. I also hadn't considered hydraulic jack fluid, so thanks for bring that to my attention.

GaryDoug

· #11 · 1 mo ago

I may be wrong here....never had a hydraulic operated convertible top, but I would guess you use normal hydraulic fluid.

Injuneer

· #12 · 1 mo ago

Spade said:
I've been using ATF. I wasn't clear in my original post; I want to make sure that if I install new cylinders that the fluid isn't damaging the seals somehow. I also hadn't considered hydraulic jack fluid, so thanks for bring that to my attention.

If you read his post carefully, he indicates the hydraulic jack oil “meets the spec”, which I'm guessing means the GM spec I posted. I'm just a dumb ol’ licensed professional (mechanical) engineer, but if it was up to me I'd choose the cited GM spec over “baby oil” or your other choices. If you end up having to buy a new cylinder, appears it will be pre-filled with the GM spec.

Reactions: 3

roorancher

· #13 · 1 mo ago

Injuneer said:
If you read his post carefully, he indicates the hydraulic jack oil “meets the spec”, which I'm guessing means the GM spec I posted. I'm just a dumb ol’ licensed professional (mechanical) engineer, but if it was up to me I'd choose the cited GM spec over “baby oil” or your other choices. If you end up having to buy a new cylinder, appears it will be pre-filled with the GM spec.

And it's not just "ANY" hydraulic oil. Only certain manufacturers/brands meet the spec. I believe it's SAE 10 ISO 32, but not sure.

Injuneer

· #14 · 1 mo ago

roorancher said:
And it's not just "ANY" hydraulic oil. Only certain manufacturers/brands meet the spec. I believe it's SAE 10 ISO 32, but not sure.

Now I'm really confused…… I don’t believe I suggested “just ANY” hydraulic oil.

So you're saying that it isn't M-H5606 hydraulic oil as indicated in the factory service manual (see my post #2)? The way I read your post (#6) it appeared you stated the same specification, although you apparently didn’t read post #2, which caused Tony to direct your attention to post#2?.?.

Please clarify for the person who started the thread.

Spade

Discussion Starter · #15 · 25 d ago

Apologies for not responding to any of this sooner. Had a few other things fixed on the car and am now re-focusing on the roof.

I came across some of the old bookmarked web pages discussing alternate fluids, but if replacement cylinders are pre-filled the logical thing to do is stick with that particular fluid. I'm certainly not going to try reinventing the wheel.

Thanks to everyone who's chimed in here. It's appreciated.

Now, has anyone actually replaced the lift cylinders? Any tips would also be appreciated.

Injuneer

· #16 · 25 d ago

The factory service manual has a detailed procedure. That's where I found the info about the cylinders being pre-filled, and the spec for the hydraulic oil.

Spade

Discussion Starter · #17 · 24 d ago

Injuneer said:
The factory service manual has a detailed procedure. That's where I found the info about the cylinders being pre-filled, and the spec for the hydraulic oil.

Still haven't found that fluid spec, but did find the replacement procedure. Thanks for reminding me to check there, and for all of your help.

Spade

Discussion Starter · #18 · 16 d ago

One more question about this... To remove the panels along the back seat I need to remove the strikers for the seat back. Does anyone know what size Torx driver is needed? Couldn't find it in the service manual.

Injuneer

· #19 · 16 d ago

Thinking back 20+ years ago, may be the same as the seatbelt anchors = T47. Just a guess, compare seatbelt anchors to the rear seat latch points to see if that makes any sense.

I also know people have “gently” hammered a T50 into the seatbelt anchors.

Spade

Discussion Starter · #20 · 16 d ago

Injuneer said:
Thinking back 20+ years ago, may be the same as the seatbelt anchors = T47. Just a guess, compare seatbelt anchors to the rear seat latch points to see if that makes any sense.

I also know people have “gently” hammered a T50 into the seatbelt anchors.

Thanks, I'll check that. Thought about locking vice grips on them but that seemed like a lousy idea. I also thought maybe they're the same as the door strikers but can't pin down that size either.

1 - 20 of 25 Posts