Bought my 93' earlier in the summer, had been driving with no issues until recently. I'm not new to rotaries, but this is my first FD. Searched around for some ideas on this issue, but wanted to try and get help diagnosing it.

Was under the car last weekend to change trans/diff fluid and noticed a slight coolant smell, but no real sign of leaks. Drove a few times this week, it's still in the mid 70's here in New England so relatively warm. Temp gauge was normal each time, never received an add coolant buzzer. I always let the car warm up for 5-10 mins before I drive off, noticed yesterday that while it is warming up it begins to drip coolant - maybe a half cup or so. Car is around 51k miles, never had smoke from the exhaust except the normal steam/condensation - also no coolant smell from exhaust. I am not sure if it is still dripping while I am driving, there is some dried coolant on the oil pan and the hoses. When I get home and shut it off though, it does not leak. On jack stands right now, the car is also not leaking.

Just to help narrow it down, I've taken the following steps:
1. Performed champagne bubble test - no abnormalities.
2. Replaced filler cap (dummy cap), visually inspected for leaks of which there are none.
3. Removed cowling under the engine, coolant pooling on the passenger side.

The car is stock with the exception of an HKS TT down pipe and an aftermarket AST which was installed by the previous owner. I am not sure of the brand, but it looks like the standard black powder coated aluminum one sold at RX7.com, Petit etc. It has one of those stant Lev-R-Vent caps.

I've taken the following pictures to help narrow it down. What are we thinking - water pump? When the car is on, the leak appears to be coming from the place circled in the first picture. The second picture is just showing where it is leaking down. Looking for confirmation before I begin ordering parts. Cheers.

 

Best way to isolate a coolant leak like that is to pressurize the system with one of those coolant system pressure test kits. Once it's pressurized, you start looking around with a flashlight for the source of the leak. If there's an Advance auto parts by you, they loan out these tools (and others) for free; just give them a credit card deposit, bring the tool back the way you got it when you're done and they refund your CC.

 

Water pump or thermostat cover gasket, or a hose clamp in the immediate vicinity? Other easy to ID possibilities are the coolant filler neck O ring, the water thermosensor, and the coolant level sensor (front side of thermostat cover).

 

@Pete_89T2 Fair enough on the pressure test kit, I will try to rent one tomorrow.

@Retserof Checked as many clamps as I could get to, they all seemed tight. I was going through the service receipts I have from the previous owner, sounds like they replaced the thermostat in 2018 or 2019. Wondering if it is as simple as the pump gasket? Possible he used some sort of compound in lieu of a gasket, or tried to reuse it. Dude seemed to have had an affinity for using instant gasket in lieu of OE parts. I even found it on the pipe fitting drain and fill plugs for the transmission.

I'll check around tomorrow and post an update if the test kit provides clarity. Otherwise, I'm thinking I'm going to crack open the water pump housing later this week and replace the pump and thermostat.

 

I would pull the air pump and inspect the 2 hoses that feed water to/from the turbos. Those are VERY common leak culprits.

That will also give you more room to see, get that tool to pressurize the system and give it a good look over.

Dale

 

Just an update, got my hands on a tester tool.
With everything out of the way, started pressurizing the system and confirmed that it was the water pump. The upon pulling it, the gasket is completely toast. Possible that it's the original one, the Mazda OE ones are orange correct?

Everything else seemed solid, the thermostat area was dry and the lines to the turbos looked fine. I have a new pump and gasket on the way from Rotary Performance, thanks for the input guys.

Cheers

 

possible, if it is an original pump it will say Kubota on it, the new one will too.

 

@j9fd3s Yeah, the original pump says Kubota. If the gasket ever had any markings on them they are long gone.

 

Food for thought...

https://www.irperformance.com/produc...ed-water-pump/

 

@TomU Haha I actually came across it this morning too. My replacement from Rotary Performance (RX7.com) is already on the UPS truck for delivery so we're too late

 

The stock pump is perfectly fine

 

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