Part Cross Reference for Caps for Cooling System

[NJGSX96]

Posted this to the TE list but figured I would post it elsewhere to broaden my audience in my search. I am looking to replace the header tank, expansion tank and chargecooler tank caps in my 1994 Esprit S4. Does anyone happen to know a cross reference part number or maybe even the Stant equivalent? I am looking to get local instead of having to send out to one of the Lotus vendors but if in the end I have to call JAE, so be it.

Thanks. Rich

[Dr.Hess]

I actually went through the entire Stant paper catalog looking for the blanking cap. Couldn't find it. If I recall, I did come across a pressure release cap of that size, but I didn't write the number down. Again, you need to see if you need the blanking cap or the pressure release one or both. My header tank takes the blanking cap and the expansion tank takes a pressure release cap. Don't have a charge cooler tank to worry about.

Dr.Hess

[NJGSX96]

Thanks for the reply Doc. I know the cap on the header tank is just a cap with a rubber seal. the charegcooler and expansion tank caps have springs (I am assuming pressure caps).

According to the manual, my car which is prior to Dec 93 and has 2 tanks, one header and one for the seperate chargecooler tank is fitted with a blanking cap for the header and the expansion tank has a 110 kPa (15 psi) pressure cap.

After the Dec 93 switchover the chargecooler system becomes integrated and the blanking cap goes on the expansion tank while the header gets the 110 kPa pressure cap. Odd..

So I guess I have the blanking cap to get. But can a blanking cap go bad? I noticed my rubber seal had 2 bubbles on the inside of it but nothing on the edges. If those are leaks, then that could cause some issues, no?

[Dr.Hess]

Yeah, blanking caps can go bad. Mine is. The rubber gets old, it starts leaking. I gave up on trying to find a replacement locally and put the one I have in a vice and gently mashed the clamping fingers down some so it grabs the neck tighter. Stopped leaking. I need to replace that one of these days.

Like I said, there is a JH that uses the same one, but it isn't listed in any catalogs either.

Dr.Hess

[NJGSX96]

OK, well no fluid leaks and I don't hear any air escaping... what happens if a blanking cap goes bad? Higher temps by chance? Air introduced into the system?

[Dr.Hess]

It leaks. You lose water out, and it doesn't hold pressure. Modern systems run at a positive pressure to increase the boiling point of the fluid. You lose that extra range between where your coolant would boil at 1 atm and at 1 atm + 10PSI or whatever the cap is set to.

Dr.Hess

[arium]

Hess is again spot on. Also, as the coolant expands into the expansion/overflow tank it cannot get drawn back into the engine as it cools. Air is replaced instead though the leak and you start your next trip with a little less coolant. And the cycle repeats....

I believe that in the Stant catalogue the only blanking cap that exists is that monster one that they show for use in the old Fieros. I think it is over 2 1/4" dia. It looks like a power steering cap than a rad cap. The others they show are for the new smaller japanese rads that look like a 1/3 scale model. I got mine from a local import dealer. The blanking caps also have narrower locking tangs than a standard pressure cap IIRC as I originally took out the inner seal and spring from a pressure cap to get me by until I got the real deal. That required a little die grinder touchup.

Steve

[NJGSX96]

A rebleed and fill of the expansion to it's preoper level and a test drive yeilded better results. Of course now I have a nice whine, like a belt whine when I gas it. Seems to be coming from the passenger side. I will check it out though. Also, the heater knob is knackered. something else to check. jeez... Anyway, I got some caps coming from JAE, just in case.

Thanks for all the advice and info.

Rich

[Dr.Hess]

Steve,
Are you saying that you found a blanking cap at an import auto parts place? Do you have any further info, that is, manufacturer, part number, vehicle it came on, etc?

Dr.Hess

[NJGSX96]

Dr.Hess said:

Steve, Are you saying that you found a blanking cap at an import auto parts place? Do you have any further info, that is, manufacturer, part number, vehicle it came on, etc? Dr.Hess

Not sure what Steve found but I called Stant and they said they had nothing like the blanking cap, nor did they make anything for a Lotus.

Spoke with Jeff from JAE and he said they are still looking for an alternative. That so far, as far as they can find, it is a Lotus only part... for now.