Having a coolant loss problem with my 95 R2 that is rather baffling. If I run the car much at all and then let it sit overnight, when I go to start it the next time the low coolant alarm goes off and I need to add maybe a cup of coolant, always about the same amount but never more than that. One time the alarm went off when I was coming back from a nearby errand, it was less than a mile away so I planned to limp home but the alarm actually stopped before I could even get halfway home.

Initially we found a leaking hose, which was replaced but the problem still continued. Then after a long period with the system pressurized they found a small leak in the water pump, so that was replaced along with most of the hoses. That seemed to solve the problem, but only for a couple of days before it resurfaced.

The coolant system holds pressure and the car has no trouble starting, the usual cloud of smoke after sitting but it clears right up. No puddles or apparent drips. Just hoping there might be some other potential cause or option to try before assuming it is a seal.

 

Check the coolant level sensor for leaks. My RX7 had the same problem, turned out that there was a tiny leak coming from where the sensor screws into the coolant filler neck. A new O-ring gasket from Ray @ Malloy Mazda was about $1.

 

Thanks, I'll check that.

Just to add more information, last night I filled the coolant at the filler neck and this morning it was down maybe 1/2" after just sitting there. Topped it off and it started right up with minimal smoke that cleared up almost immediately. Ran several errands from less than a mile away to about 12 miles away with no problems. But I noted later that the overflow reservior was above full, it almost seems like coolant is going there and not getting back. I also forgot to mention that I have a Pettit aluminum AST.

 

Search much?

You can also try the thread in the FAQ thread stickied in this forum
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

Scroll down to the C section and go to this thread
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/

If it holds pressure as you say, then there isn't a leak. There is probably air in the system as you will learn if/when you read that thread. Keep 'burping'.

 

I did search first, through several pages, but don't recall finding that thread, so thanks for the links. I guess I assumed that would have been addressed when they replaced the water pump and hoses, but maybe it wasn't.