dfwrx7

Has anyone used rubber washers on a GSL-SE or 79-82 oil cooler? It seems to me that if rubber o-rings work under filter towers then modern rubber washers should be able to handle temperatures and pressures at the oil cooler. Having just had the second bung on my -SE oil cooler fixed I'm looking for alternatives. If/when my cooler cracks again I'm just going to have -AN fittings welded on so this is only an interim fix but one I'd like to use at least through the end of the race season.

Rogue_Wulff

Ah, but the filter towers have depressions for the orings to sit in, so they can hold the pressure. Oil cooler hoses do not have a groove for the oring to sit in, therefore, would likely not be able to handle the pressure.
Are you using new sealing washers everytime you re-install the lines? I prefer to use copper washers, rather than aluminum. They seem to seal easier, without requiring quite as much torque.

trochoid

iTrader: (6)

Absolutely will not work, sorry. Rubber o-rings are captured, that is how they stay in place and seal. Even on my Mallory Comp fuel pump, which has a captured o-ring, is leaking at less than 18 psi.

Crush washers are a one time use only and reusing them is one of the main causes of the 1st gen fmoc bungs cracking. They will not reseal, yet owners keep trying to get them to reseal, until they crack the bung from over tightening, and end up with 2 places that leak.

dfwrx7

C'mon guys. Read, don't assume. I'm talking about replacing the copper/aluminum crush washers with rubber washers, not o-rings. I know o-rings require a machined grove. I also know that several people have had their oil coolers machined to accept o-rings with good results. Rubber/nitrile/viton washers may be an alternative to copper crush washers that do nothing except close the gap between a good seal and cracking the oil cooler bungs. If another material can widen that threshold without compromising the integrity of the seal why not use it? Modern elastomers should be able to handle the temperatures and pressures involved. I'm wondering if anyone else has even investigated that posibility.

Rogue_Wulff

A rubber washer, with a metal band around the outer edge, might work fine. I wouldn't try one without the metal band, though.

dfwrx7

Yes. My process (which I wouldn't expect you to know since you've not been under the car with me) is to make all the joints hand tight, start the engine, examing any leaks and address them with minimal tightening. All fittings so equipped get a backup wrench to prevent any undue torque on the back side of the joint. Repeat until no leaks are present. Wait for the engine to cool off completely, clean all joints and restart while looking for leaks. Wait for it to reach normal operating tempurature, check for leaks again and citing no leaks slowly rev to the top of the rev range while observing oil pressure. Bring back to idle and check for leaks again. My car has had -AN equiped braided hoses for the last 7 years. Every time the -AN adapters on the oil cooler come off they get new copper crush washers. This worked fine when I had my oil cooler off last time some five years ago. I'm just sick and tired of messing with oil coolers that are prone to crack and leak. Even the spare that I had which I thought was crack free ended up being cracked on both bungs. Absolutely aggrevating.

Mine started leaking some time last year. Fortunately the local SCCA Safety Steward is a RX-7 guy and knew exactly what I was talking about. FWIW, he doesn't use a Mazda oil cooler on his car. I believe his is a Setrab that is the width of the radiator and about 8" tall and 2" thick.

dfwrx7

I'd seen some like that. I might pick some up if they have the right size. Those folks using o-rings in recessed grooves haven't had any trouble and I know at least one that doesn't need to seat his -AN adapter completely for the o-ring to compress and seal correctly. I'm leaning toward the metal washer with an interior rubber insert if I can find one in M14 to fit over my adapters.

I think this might be the winner. If I can find them locally rather than having to wait for mail-order I'd definately go for that. I've got an autocross this Sunday with my Dad that I'd rather not miss if possible.

http://store.summitracing.com/partde...5&autoview=sku

Rogue_Wulff

I went with an FC oil cooler when I tossed the beehive. These seem to have better attachment bungs than the SA/FB cooler had. Banjo bolts vs the screw in ends.

Rogue_Wulff

Those items from summit should work. I'd get an extra pair, just to be safe. I bet you could find something similar at a local speed shop.

dfwrx7

Yup, the FC oil cooler seems to be a popular replacement. I'll probably go with a different oil cooler from Mazda Motorsport when I replace the GSL-SE cooler. The FC cooler is fine but if I'm going to fabricate new mounts I might as well add a bit more cooling capacity since it's a track car subject to long periods of idle in the paddock in north central Texas. It's been 100F all last week and thus far this week. So far the forcast for Sunday is "only" lower nineties or perhaps as cooler as upper eighties.

Rogue_Wulff

FC cooler is also easier to eliminate the thermal bypass. A mod I highly reccomend for a track car. Why bypass the cooler until the oil reaches ~160F?
I had my '83 on the track at MSR last month, and with temps in the mid 90's, I had no heating issues. Even had far less underhood heat after a session than my buddy who has an SA.

trochoid

iTrader: (6)

I have to say, you have the tightening sequence down to an art. Best way I've found to do it.

Fwiw, one of the engines I tore down had plastic washers under the oil pedistal, which apparently did not leak. The cross-section between the inner and outer diameters was about 3 times the width of the stock o-rings and they were about 25% thicker.

Have no idea what type of plastic they were, other than hard and white.