Mazdax605 Reader
Dec. 1, 2009 6:31 p.m.

Hey guys,

On my 78 RX-7 GS which I just re-installed the freshly rebuilt factory engine(12A) I have a coolant leak that is external of the engine. I know this because I have some splashes of coolant on pats of the engine bay,and mostly focused on the passengers(right) side of the engine bay. I have a pressurizer for the radiator,and I have put it on,and pumped it up to 15 psi,and let it sit for a bit while looking for the leak. I can't find it,but I did tighten up the radiator hose connections which are on that side of the bay. It will lose about 3 psi over an hour,but I have no puddles,ar trails of green that I can see in the cooling system.

I know it isn't getting into the engine as I would have a sweet smelling exhaust,and white smoke which I have none of. I also trust the builder of the engine,and doubt the coolant is leaking into the engine,plus the splashing of coolant in the engine bay. It looks as if the engine driven fan is picking up the leak,and blowing it around,but mostly in the right side of the bay.

Any help would be appreciated.

Chris

Mazdax605 Reader
Dec. 1, 2009 9:21 p.m.

So I just checked again,and over three hours I have lost 4 psi on the pressure tester. I still don't see any visible leaks now that the hose clamps have been re-tightened,but I am still losing some pressure. Any help is appreciated.

Chris

sevenracer New Reader
Dec. 1, 2009 9:48 p.m.

In reply to Mazdax605:

You don't say where on the pass side, but I would look very closely at the heater hoses where they go through the firewall and the hose that connects the rad to the heater hard piping. Those get brittle over time.

Also, the 2 o-rings that seal the coolant passages of the intake mani to the block. You should have gotten 2 new ones with your engine rebuild kit. Maybe one isn't seated correctly?

RexSeven Dork
Dec. 1, 2009 9:52 p.m.

In reply to Mazdax605:

I may be in the area on Saturday or Sunday to pick up an SRI for my MS3 (depends on if it gets sold or not before the weekend). If I do get the part, I could drop by your place and help you find/fix the leak if you like.

Mazdax605 Reader
Dec. 1, 2009 10:18 p.m.

I have replaced the two heater hoses. The leak seem to be in the area of the radiator. I think maybe the hose clamps were just a bit loose,but I am still concerned that I am losing a few psi over a few hours. The coolant o-rings on the intake manifold were new,and I have never had an issue with them in the past on a rotary,but did on the old L20B in the Datsun this past winter..

It really appears to be an external leak,and if the o-rings were leaking I would think they would leak into the engine a bit,and burn off as white smoke,but maybe I am wrong.

Chris

44Dwarf HalfDork
Dec. 2, 2009 6:21 a.m.

1) Water the motor. 2) Blow dry with exhust from shop vac or compressed air. 3) Spray the cheapest foot anti-fungal spray on motor and all conections. 4) when spray turns white pump up the coolant system. 5) Look for wet spot.

44 PS works great for oil leaks too!

John Brown SuperDork
Dec. 2, 2009 6:42 a.m.

Plus you have the benefit of a fungus free engine.

minimac Dork
Dec. 2, 2009 7:00 a.m.

Have you checked the heater core ?

Kentetsu New Reader
Dec. 2, 2009 9:44 a.m.

Is the overflow tank, umm, overflowing?

Mazdax605 Reader
Dec. 2, 2009 12:55 p.m.

It is not the heater core. The over flow tank is also not the problem,either. I really think it was a few semi-loose clamps,but I stil don't know why I am losing a few psi of pressure,but no visible leaks,or puddles. I had the system pumped up to 15 last night,and when I checked it this morning it still had 11 psi on it. Is that an acceptable amount to lose over 7-8 hours? I remember someone telling me that air can leak out in places the coolant can't. Does that sound right?

benzbaron Reader
Dec. 2, 2009 2:11 p.m.

I had a wicked little leak in my toyota pickup that was really hard to diagnose. It turned out to be a combination of a pinhole in the cylinder head and a slighly warped exhaust manifold. I don't know if any of that applies to your situation.

You'll need to log in to post.

Also on Grassroots Motorsports

Follow Us to the Nürburgring

4 hours ago in News

Follow along as James Clay from BimmerWorld contests his first ADAC Zurich 24-Hour race at the Nürburgring.

You Need This: 2005 Lotus Elise

4 hours ago in News

A Lotus Elise looks so right in British Racing Green.

2017 Mazda MX-5 RF

6 hours ago in New Car Reviews

We're big fans of the Mazda MX-5. Now Mazda went and put a retractable fastback on their fourth-generation car. So, ...

From the GRM Vault: Test Driving BMW's E30 M3

9 hours ago in Articles

We tested BMW's E30-chassis M3 back in 1989. Here's what we thought.

Project Ramp Truck: Installing Sound Deadening

11 hours ago in Project Cars

Time to cut down on heat and road noise making its way into the cab.

Eric Foss Sets Fastest Time Ever at the Tire Rack Ultimate Track Car Challenge

1 day ago in News

47 of the country's fastest cars battled it out for track supremacy.

Who Wants to Design the Next GRM T-Shirt?

1 day ago in News

Blipshift is involved, so you know that it will be cool.

Reader's Ride of the Week: Improving Upon the Ultimate Driving Machine

1 day ago in News

This E36-chassis M3 just keeps getting better.

What Was the Most Powerful Car at the Grassroots Motorsports Dyno Day?

1 day ago in News

What if we told you it was an Audi?

Up to the Challenge

4 days ago in Articles

Torque: It's how Glen Bunch's vintage Dodge keeps pace with today's machines.

This Friday: The Ultimate Track Car Showdown

5 days ago in News

Come watch some of the country’s top track cars duke it out for fame, glory and some tasty prizes.

You Need This: Metallic Brown Toyota Celica

5 days ago in News

This looks a lot like one that we had in our fleet back in the day.

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
195SPEZ4IS1xQMgUUd7AdRuETU7oViV8