Help fix oil leak at oil cooler?
 

I tried a search but maybe didn't use the right keywords.

I have located the source of an oil leak on my GSL-SE. It appears to be coming from the fittings at the oil cooler. Do the lines or cooler itself have to be replaced? Not sure how to proceed.

First picture is the lower hose. Next, a sensor. Then, the lower hose fitting. And finally the upper hose fitting.

Thanks,
Seamus

Go to Mazdatrix.com and order the proper cruch washers. This is a high pressure area and that plastic seal washer will not cut it. Do not use silicone in this area, it will do no good.
After getting the crusher washers, use some red or blue Loc-tite, and tighten fitting fairly good. Be sure when you attach the hose to the cooler fitting that you use two wrenches. (this area is where people over tighten and crack the oil cooler)
If you want to go ahead and upgrade the oil cooler lines you can order the Stainless Steal braided hoses as a kit (all fittings and washers included).

happy wrenchin'

What my fellow rotor head has stated with the exception.
Do not recommend red loctite unless you don't want to get it back off. Never had the need for loctite on these fittings but if you do use, then use the low strength.
When tightening only tighten until snug then slightly past. Run engine and test for leaks.

Thanks! Very helpful. I understand about the caution concerning the the loctite. What the heck pipe sealant is that in my pictures? Do I need a teflon pipe sealant or similar?

AFAIK Keep tefllon tape away from any part of the engine that see's its internals, ie Oil coolers, Carburetors, Intake manifolds, etc.

I have a slight leak on my oil cooler also... It started out of nowhere & it's on the upper hose that connects to my 2nd Gen front mount oil cooler. The lines are new from a hydrolic / truck shop.

I'm hoping it's as simple as replacing the crush washer..???

It's a very small drip that's starting to slowly make a mess.

as long as you dont apply liquid teflon or teflon tape on the first 3 threads, you should be fine. thats to ensure that it doesnt go inside.

And always use 2 wrenches when installing the OC lines. one to hold the fitting in place or prevent it from turning and cracking the OC. The other to tighten the OC line end.

If the leaking persists after you replace the crush washers. Check the acctual Oil Cooler itself for hairline fractures along the threaded portion where the oil lines feed into.

I had this problem with my 1982 about a few months ago. When I went to replace my crush washers and do an oil change i bled about a pint in just cranking the car over. The replacement of the crush washers had caused the crack to become worse and the mild leak turn into a serious one.

But yeah, if its been a constant leak, while you have the lines off, just make sure you don't have any cracks.

If it is cracked you can have it welded to repair it like I did several years ago. Now I wish I had upgraded to stainless lines instead of OEM but the oil cooler is still one of the few places I DONT leak oil!

BEFORE you replace the crush weashers, pull the oil cooler and check the bungs for cracks. even the slightest crack will yield a nasty leak. most people have trouble after replacing the crush washers or lines. the problem is that they ovetighen the lines and crack the bungs. i found out the hard way myself. tighten until snug and then just a hair past that. maybe a 1/4 turn or less. but make sure you are checking the cooler. the stress from bad mounts can crack the bungs. i found this out the hard way as well.

So now I am concerned about cracking it. What is the right way to remove the lines? The fastener closest to the cooler, in contact with the plastic washer, moves easy enough but the whole line is turning with it. Don't want to break anything.

Thanks,
Seamus

I ended up forking over the cash for new oil cooler lines and just cut the old one with a large serrated kitchen knife. That one was turning on me, too.

On your's, use two wrenches and break the fitting farther from the fmoc loose, holding the inner one in a static position, from the looks of the type of fittings you have, you should be able to spin off the outer connection, leaving the adapter screwed in, then remove the adapter. What year of car is this? The fmoc fittings look different than the one's I'm familiar with.

One thing that makes the 2nd gen fmocs superior to the earlier ones is the use of banjo bolts instead of tapered threads. I have yet to see a cracked bung on a 2nd gen fmoc. The biggest reasons these leak is the mating surfaces for crush washers were not properly cleaned and/or the crush washers were over tightened.

Pick up new crush washers, clean the mating surfaces, the bung on the fmoc may need a very light sanding to remove the ridge of gunk that tends to build up. Use a can of brake cleaner for cleaning, great stuff for removing greasy deposits/films.

When you reinstall the banjos, hand tighten, the turn 1/4 turn with a wrendh. Now start the engine, you will probably have a leak, slowly tightetn the banjo until the leak stops. Recheck for leaks after the engine has gone through a couple of heat cycles.

This car is an '85 GSL-SE.

I have the exact same car but my fittings weren't plastic. They were metal and had crush washers. That's what he's talking about by ones he's not familiar with.

Nope, I'm, talking about the height of the bungs on the fmoc, they look too short. I've repaired cracked bungs on SE and 79 fmocs, neither of them had bungs that short.

dont mean to threadjack but i heard that most aluminum welders wont even bother to weld a cracked oil cooler for liability purposes because since it has oil, it can cause a dangerous fire or even if you take it to a radiator shop and have the cooler cleaned out, they still wont fix it because if it wasnt really fixed and the crack becomes worse and causes you to lose all your oil and your engine die, then they would be in trouble. correct me if im wrong but this is what a rotary mechanic told me.

demonspon67.. how did your oc fix go for you/ how much

Did oil flow up the mounts and on to the radiator?


I had mine fixed at a local welding shop for $30.

It wasn't leaking, but it had some cracks around the bungs that I didn't want to chance.
http://homepage.mac.com/jolocho/coolerFixed.jpg

I've taken my repairs to the local motocylce dealer/repair shop. 15 bucks and never had a refusal. I do clean out the fmoc and v-notch the crack before taking them in for tigging. A friend of mine found this shop, after getting some outrageous estimates from other shops.

thanks trochoid but how do you v-notch. so you cut into a v shape and wedge a piece of aluminum in there?

I use a 1/8" carbide burr, so techically it's a u-notch. This allows the welder to achieve better penetration and seal the crack deeper than a surface weld could.

You were correct. Only problem was that SOB was so tight it just would not break loose. I had to remove the fitting at the block and spin the whole hose off. Then, it still wouldn't come loose. I had to break it with an air gun. Guess that's 23 years of heat and sitting.

That brings me to the top hose. I have the same problem there. Trouble is the fitting at the block is identical to the one at the cooler and looks like it would require removal of the motor mount bracket to break it free. I am trying some PB Blaster (ie liquid wrench) on the top front fitting and going out for awhile.

The top fitting was finger loose when I found it. That alone might have been the cause of my leak. If I can't get it off I am just going to tighten it back up and see if that fixes it, unless there is some other trick to try.

Thanks,
Seamus

i have had a local machine shop fix 2 that had cracks in the bungs, $25-$30 and they hot tank it. be sure to take out the oil thermostat before letting the machine/welding shop guys have it :)


isaac

The top hose on the front cover can get irritating. It's a similiar fitting, but the adapter is different. The hose must be broken loose from the adapter fitting first. That fitting shouldn't be as tight as the front one, but access is the biggest headache. I've had to remove the radiator before to get to a stubborn one. I've had to grind down the thickness of one of my standard wrenches to get it to slip over the inner part of the adapter fitting. This is another 2 wrench job.

Do not reuse the plastic washers, you will be wasting all your time and effort. They will never seals, nor remain tight enough. If you tighten them down too much when they continue to leak, you WILL split the bung on the fmoc.