I'm about to throw in the towel in my missing coolant issue. This applies to a 1993 RX-7 R1:

Facts

- No white smoke out of the exhaust after warm-up. Very little during initial cold morning start-up.

- Aftermarket aluminum AST

- Replaced radiator (Fluidyne), radiator hoses (SAMCO), and various front-end coolant hoses (OEM). Replaced coolant w/ fresh mixture approximately 3 days ago. Went through burping process twice since (I disconnected the coolant line by the intake elbow during the burps).

- No obvious leaks

- Car pulls very strong

- Coolant temps stay around 84 - 88*C (occasional random spikes to 90 - 95, but very brief) during a typical day of driving around the surface streets

- Need to add about a medicine cup of water about once a day to reach about 1" from the top of the coolant-filler neck (granted its only been 3 days since I replaced the radiator, but I'm getting a little paranoid since this issue was present before I replaced the radiator and hoses).


At this point the paranoid side of me is suspicious of a bad coolant seal, but I would like to have a shop confirm this through pressure testing before I make the dive on an engine rebuild. Any recommendations? Bonus points for being close to Kent, Renton, or Seattle.

Thanks!

- Nate

 

Have you checked for minor leaks in all your hoses and joints?

If so, I know there are some people in your area, not shops, that would be a good help

 

Have you tried Jerry's little car shop or something like that? I have heard several people in your area talk about his work, and I have a customer that got a car from near Seattle that just had a compression test done by him. Don't know if he would be able to do a coolant system test for you or not but its worth a call at least. If not I'm sure Tim ^ Knows one or two people that could help you out Good luck!!

 

I've tried inspecting the hoses that I've been able to get to. I have not been able to check the hoses by the turbo, UIM, and LIM. So far nothing obvious or no signs of leakages around the corners.

Originally the new samco hoses were leaking around the edges where I had used the OEM clamps, but I've since replaced them with constant-torque clamps and have observed no more leaking.

I'm considering contacting Jerry's little car shop. I thought I'd consult the board locals first to see who they've had success with.

 

Jerry's is a good one. I think he is reasonable in price. And I think he is in Tacoma?

Have you noticed any breakup in your ignition at all since you've started losing coolant? If you can try pulling your plugs and see if you're getting any coolant on them. Unless you would rather have Jerry's check it out. I have seen many a failed coolant seal without the white smoke, so I never really look for the smoke, just the other signs like losing fluids, bubbles in the coolant, carbon flakes in the coolant, black overflow dipstick, etc.....

 

I'm in renton, let me check your stuff out. I got some tricks I can try on it. I bet it's fine. Seriously, don't let any shops take your money, cause that is all they will do.

 

..says the man with the blown RE lol jk

Jerry's is good, dealt with him a couple times but never brought my car there. shop is located in Kent

 

Jerry's is sounding pretty promising. I checked out the website, he's pretty close to me which is nice.

Tweak - I'll IM you later on tonight, maybe we can figure this out together before I resort to booking time at a shop. I hope that I'm making a big deal out of nothing... now that this car finally has some power, it would be pretty lame if I had to do even more maintanence.

Additional Facts (so far):

- Overflow dip stick is clear

- Coolant appears to be very clean with no visible contaminants

- Added another medicine cup worth of distilled water to the coolant filler neck this morning. Overflow tank was full with no signs of fluid loss.

 

Update:

Went out to check the coolant level during my lunch break today. Noticed that the car had "wet" itself in the parking lot...

I guess the good news is that now I know where some of the coolant is going...

Now I've got to determine where and why... a quick look shows that it might be coming from the lower radiator area? Possibly one of the ends of the lower radiator hose, or possibly from the AST line down there?

I may head over to a friend's place after work to put the car back up, tighten my constant torque clamps down there, and maybe throw on a worm-drive clamp for the AST line (I'm really begining to distrust the OEM clamps!)...

 

Not my fault! lol. BDC botched my primary ports. :'-( My engine was a ticking time bomb. Every time I stopped or started my engine, it died a little, and so did I. :P


Anyways, I'm sure we can find out what is going on. There is a good chance you either still have some tiny air bubbles in the system, and or you have a TINY TINY TINY coolant leak that only leaks when the car is super warm, and you are moving, water pump is creating pressure ect ect. I have had tons of these. The smallest buggers are the hardest ones to find! We will find it!

 

Opps, posted while I was posting. Great news, yeah, don't only look at the ENDS of the hose where it connects to things, quite often the hose can develop a small sub pin hole ... sized hole, that will seal perfectly 90% of the time, but grow larger and more flexible as the engine (and rubber hose) gets warm. Honestly after doing a quick look around just to check thing, I would go drive the car hard, and then keep it idling (with the hood up rev it with your hand on the throttle body) and I'm sure sure the leak will show itself. Don't go too far from home.

 

Maybe your new radiator has a leak - it's happened to me before.
m

 

Really easy to just see where its leaking at in your engine bay, as in if it goes from the top area of ur engine bay down or just down low. something to look into if you havent

 

If you still have your undertray that should help point you in the proper direction, if it's coming out of the overflow then we have some deeper issues here.... Let's hope that's not the culprit

 

Thanks for the tips guys!

As far as I can tell, nothing is coming from the over-flow tank or anywhere else in the engine bay. For the longest time it appeared that the upper radiator hose was the culprit. I put two clamps (one constant torque, one worm drive) on the connection point and torqued them down as much as possible w/o breaking the clamps. A small amount of water was still forming around the upper connection point to the engine block after this.

I think I've narrowed it down to the coolant level sensor on the coolant filler neck. When I squeeze the upper radiator hose while burping the coolant system, I noticed some water tearing out of the edges of where the sensor screws into the neck. This water would eventually snake its way down and pool up on the top edge of the upper radiator hose.

I've ordered a new coolant level sensor (the wiring connection on mine is exposed/shoddy) and a new OEM O-ring gasket from Ray @ Malloy Mazda. Parts should be here Thursday, I'm hoping that this is it.

 

I wanted to thank everyone again for offering their advice while I was trouble shooting this issue. My problem turned out to be a slow leak coming from the coolant level sensor. Replaced the sensor and O-ring, reburped. No more volume loss. No more issues.

Drove the car spiritedly today through the warm weather, coolant temps stayed around the 87*C range on my PFC