88 TII.

The past few days my add coolant buzzer has been going off. So I changed the thermostat and added new coolant.

After I replaced the thermostat, I was adding coolant and it started leaking where I had just put the new gasket on. So I took it back and and fixed it.

Later I was driving and my car started smoking really bad and I could smell that sweet coolant smell. I stopped, popped open the hood and it was too dark to see where it was leaking. I just assumed that it was leaking from that stupid gasket again.

Then today I went to warm my car up before bringing it in to work on that thermstat/gasket. When I pulled it into my garage and opened the hood to see where it was leaking, it was wet with coolant all by the back of the engine on the left side if you were looking at it from the front of the car. All the vacuum hoses that make up the "rats nest" were wet too. Then the EGR valve was also. Coolant was pooling up underneath it that little metal tray below it. At least I'm pretty sure it's the EGR valve... and if not, you'll probably know what I am talking about.

I looked where it could be leaking from, but I could not find the source. Anything I might want to check out around that area? All hoses from the intercooler are fine.

Thanks,
Jordan

 

Does it look like it's under the UIM, near/under the injectors?

(pic is from an older thread by another user I found when I had this problem)

If that is the case, you're o-rings between your "block" and LIM may be shot. You can buy them on from www.mazdatrix.com They will be long process to replace. You will need to remove the IUM (easy), LIM, which will be tough because you need to remove the turbo to get to the bolts. Good luck! makre sure you get a replacement gasket too!

You can see the o-rings in my pic

 

maybe the thermowax hoses are leaking. let the car idle for a few minutes and build up coolent pressure. add coolent as needed of course. while the car is still running gently squeeze the hoses and see if anything bubbles or splurts out.

 

Hmmm, that could be it, though the pooling was more in the rear, maybe the rear o-ring is peacing out. I'll have to take another look tomorrow and see. But yeah, I've removed the upper intake manifold before so that should be easy. Not the lower manifold, nor the turbo. I plan on getting the RB exhaust and some other stuff, so I guess it wouldn't be a bad idea to just port my wastegate now while the turbo is off; that is if the o-rings are shot.

Thanks for the information Beefhole, it was really helpful. I guess I'll just have to see it that's what it is. By the way, why do those o-rings go bad? Any other reasons other than age I should be worried about?



I'll check that tomorrow too. When I replaced the vacuum hoses, all my other hoses seemed to look fine though. Well, you can never be too sure I guess. Thanks for the info.

 

I had this same problem with my 88tII a long time ago. You mentioned that you replaced the thermostat. Ok, on mine I had a hairline crack on the plastic thermostat housing. It must of cracked from over tightening. So take a good look at the housing to see if its cracked if it is and you are thinking of buying a new plastic housing DONT. Be sure to buy a housing for a FD because they are made out of aluminum. I just figured why go back with a new plastic housing when aluminum will hold up better. My memory isnt all that great sometimes but I don’t think the one for the FD wasnt much more expensive than the on for the S4 FC.

Also, NCross has a good point. There are a lot of small coolant hoses going to the intake around that area (termowax, BAC valve and intake) it could be possible that it could be one of those hoses.

You could rent a pressure tester from your local parts store. That way you could pressure up the coolant system while the engine is not running that way you don’t have to worry about getting burnt while looking for your leak.

I haven’t seen to many rotaries leak at the LIM, but I guess at this point any thing is a possibility.

 

Plastic housing? There isn't any plastic on my thermostat. But I'll check that too.

Also, when the coolant was leaking, there was a steady drop of it and landing on the exhaust right next to the O2 sensor. I don't know if this tells anything or not, but I couldn't see where it was coming from. I'm going to go out there and see.

 

Mine had the same hairline crack. I was pissed when I replaced it with a stock piece from Mazda. It cost 106 BUX PLUS hthe seal. I could have bought an Aluminum one from Mazdatrix for 120!! I didn't know about the FD neck though.

 

One would expect and O-ring to fail on such an old car like our FC's especially since there is a probably a lot of heat in that area. Mine was pooling in the rear and not the front, but that's because my gasket blew in the rear. Previous owner/engine builder didn't even install the o-rings Hope you find your problem.