Just a couple of hours ago I was on my was to Mass in my XJS, admittedly, pushing 95 mph on an empty road and suddenly a huge cloud of smoke on my rearview mirror and out of my the sides. I pull over with my fire extinguisher just in case and open her bonnet, red transmission fluid all over the entire front of my engine. All over my brand new fan shroud, brand new cam cover,all over my relays , just all over the engine but mainly in front. I check the level on the tranny and it has gone down but not empty. I baby her home, and no Mass, a dirty engine and a very expensive sports coat with trans fluid stains all over.

I have had both hoses remade and replaced by my mechanic. One of them has already bust once before but at low speed. No drama like today.


Does this sound like one of the hoses again to y'all ?

 

Merry Christmas to you. Sorry about your sport coat and nice clean engine bay. I just bought my XJS a month or so ago and I took it to the dealer for an inspection. One of the many things they told me was that the power steering hoses were leaking and should be replaced. I haven't done it yet but your story reminds me that it would be a good idea.

I hope the rest of your Christmas goes better!

 

Where did the failure occur?

What hose was used? What clams were used? Transmission cooler hoses should meet SAE J20R3, D1 specifications which are for high temp and pressure hydraulic fluid.

Normal hose clams usually can't handle transmission line pressure for long. consider using oetiker clamps.

 

Sounds familiar except that my tranny hose ruptured at the rear of the engine block and set my engine bay on fire because the fluid got on the hot exhaust You were lucky. I replaced my tranny cooler hoses with steel reinforced high pressure hoses routed away from the engine.
RagJag.

 

I'm not at all an expert but didn't think that pressures were that high in the cooler lines - weren't the hoses on earlier xjs's clamped on at the radiator? I'd like to know because I recently replaced my trans cooler hoses when replacing the radiator and the hoses I had made, while good quality, probably don't meet that sae spec. The original equipment hoses don't seem to have any wire or braid reinforcement either, they aren't nearly as stiff as regular hydraulic hoses. I've used these new hoses about 1k miles so far.

 

I don't think the 95 mph speed had anything to do with the hose failure. I also think the tranny may at most have 60 PSI on the cooler hose. Probably closer to 40 PSI. The hose your mechanic put on was obviously not heavy duty enough for hydraulic service.
Cheers, RagJag.

 

Well I won't know what is wrong until the new year since my mechanic has apearantly taken the rest of the year of. I might try to get on there and see what us going on.

 

Not that I launched an in-depth probe into the matter but I perused several different service manuals (covering various GM, Borg Warner, and ZF tranmissions) I couldn't find any info on what kind of pressures to expect in the cooler line circuit.

My guess is 30 psi. Some Googling indicates others guessing about the same. It might be something that varies a fair bit depending on design but I can't imagine designers/engineers *wanting* an unusually high pressure. No good would ever come from it.

I'm sure more info is out there for someone wanting to dig.

Going out on a limb but I just gotta think that any hose that says "hydraulic use" or "transmission cooler" on it should tolerate 40-50 psi with no problem. Probably more, even without getting into industrial/exotic stuff.

FWIW I've seen umpteen cars with ordinary hose clamps on the cooler hoses. My Ser III XJ6 came that way from the factory, in fact.

Examination of the failed hose should be revealing. A failed crimp is a failed crimp. If the hose itself burst open then that's a different matter, of course.

One thought, a bit premature, is that there might be a restriction in the cooler circuit which would drive pressures higher than intended.

My money's on a faulty crimp.


Cheers
DD

 

Thanks everyone for their replies.

The transmission fluid is mainly on the fan cowl flaps, all over the a/c compressor and has slashed on the other end to the relays. Where should I look for a loose crimp or connection ?

 

The trans cooler pipes run along the RH side of the engine under the exhaust manifolds fixed to the block, these are steel pipes. There are 2 flexible hoses from just behind the alternator to the RH side of the radiator, check these hoses. There are also 2 flexible hoses from the rear of the steel pipes to the trans, if the mess is at the front these are probably ok.

 

Thanks for the reply. It was the clamps on the re-made flexible hose part. I am now very confused on what about my transmission lines was "re-made", since to me it just looks like the original rubber hoses where chopped of and new common hoses fitted.

At any rate it seems like the clamps are made out of goo. Does anyone know of clamps that are not garbage?

Thanks

 

My car still has the original trans cooler hoses and on the radiator end (I have not looked at the other end) they have swaged fittings, NO clamps.

 

Lots of junky clamps out there.

Not quite sure what you mean by "made of goo", though.

Anyhow....

Lowes and Home Depot carry some decent stainless steel clamps that are better then what most auto parts stores are selling these days.

"Jubilee" brand stainless clamps are very rugged. XKs Unlimited has them....or they did years ago.

Oetiker clamps are good as well. These are a crimp-on clamp. Just Google it; you'll see.

Cheers
DD

 

Thanks Doug.

I have been lurking around other car forums and it looks like ABA Swedish clamps are one of the most trusted ones out there. I am getting some of those

 

ABA is a good choice; essentially the same as the Jubilee.

The important aspects are heavy construction (no distortion when tightening) and smooth inner surface (doesn't cut into the rubber)

Cheers
DD