Hi guys, im a bit new rotary engines. I have a 93 fd rx7. parked my car in the garage and noticed that my my hood was steaming a bit. Opened the hood to heae a hissing noise and some pressure from from what felt was from the left side of the intake manifold when facing the front of the car. I was wondering what it could be. any help is appreciated.

On another day I started the car in the garage and got it to running temps to see if it would steam again. however I didn't see any steam nor hear any hissing noises. I even to it around locally and drive back home and still no steam or hissing noise from under the hood. prob drove 3-4 miles. There is no oil leaks or coolant leaks dripping from under the car at all.

 

There's nothing necessarily unique to fixing a coolant leak on a rotary vs. a piston engine. Find the leaking hose, fitting, gasket etc and replace as necessary. You might want to check your coolant level now, and if it reappears, use a flashlight to see if you can find the source.

 

After the car has completely cooled over night, open the cap on the filler neck (attached to the engine) and make sure it is filled to the top with coolant. If it isn't, you likely have an issue.

Pressure from left of the intake manifold isn't likely to be a coolant leak (based on what's over there). A picture or video of what you're seeing would also help dramatically.

 

I'm going to guess at the turbo coolant line under the air pump has gotten hard and brittle and and is leaking coolant.
You can do a cooling aka radiator system pressure test to try and pinpoint the location of the coolant leak FYI.

 

There’s a really helpful coolant system routing diagram in the Factory Service Manual. The FSM is available for a free download.

 

so i filled up my coolant and borrowed a friends coolant tester. I pumped to about 16 psi. I lose roughly 1 psi a minute.

using the coolant diagram i don't see any leaks from:
AST pressure relief to overflow tank
from rad to WP
AST to rad
From thermostat to rad
from thermostat to AST

what i did find is some dried up coolant on the bottom left corner hoses of the intake manifold and a line near the oil pan. does anyone know what lines these are? no coolant leaks found on the cardboard I put under the rx7.

If anyone can also help me with directions to what to take apart to reach the turbo lines, it would also be helpful.

 

1. Your pictures are at pretty bad angles, try to do better in the future. I think it would be easier to see what you're showing if both were zoomed out further for better context.


2. I agree with the others, turbo coolant lines are the most likely cause of coolant leaks in that area. It was a known problem 15+ years ago when websites looked like this: https://robrobinette.com/turbo_lines.htm . All the advice from that page is still good. I've replaced those exact hoses twice, they do get in worse condition than all the other coolant hoses in the engine bay. Get new OEM hoses, they are cheap and molded to fit well. I like buying from Ray Crowe (search forums for his contact info), or from Atkins. or from Mazdatrix. Use a razor knife to cut the old hoses off, there isn't a lot of room to pull them off. Lubricate the inside of the new ones with coolant or soapy water, the area is tight and they will be tough to install. Get a Lisle spill-free funnel for refilling and burping the cooling system, they are great. You will need to continue checking the coolant level and topping off for the next few trips after refilling it.

 

Yep, most likely the turbo hoses. If you remove the air pump you should have a world of room to see and get to them. They aren't too bad to do, I had to replace one myself in a parking lot once and it didn't take much time at all.

Long needle nose pliers make all the difference for removing the hose clamps.

Dale

 

thanks for the assurance guys. I really appreciate it.

 

would i need to take out all the coolant to replace the turbo hoses?

 

no

 

Your going to lose some coolant, so you’ll need to have some on-hand. But it’s not necessary to drain it completely.
Search in the tech section with terms like “burping” for info on how to purge the system of air afterward.

 

can anyone guide me on how to properly uninstall the air pump?

 

1: Remove both of these clamps and remove the hose.
2: Unplug the pump by disconnecting this plug.

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1: Remove both of these bolts. The air pump is now free, you can lift it out and set it aside.

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is this correct?

 

are these the correct part numbers for the turbo coolant lines?

N3A1-13-536
N3A1-13-54X

or are both lines
N3A1-13-54X

 

You need those 2 part numbers, one is the top hose, one is the bottom hose.

Air pump is pretty easy to remove, all bolts are obvious. If you have a stock airbox it may be worth removing it to give some more room.

Airpump is 1 bolt up top, one bolt on the bottom, 2 air lines (one to airbox, one going back to engine) and 1 electrical connector.

I think removing the bolts will let you de-tension the belt enough to slip the belt off.

Dale

 

You can get the hoses from Ray Crowe. If you search, you will see a lot of good history with him. He offers us OEM parts at a massive discount and excellent service.
Email him at crowe.ray@aol.com

You don't need to research part numbers with him since he's an FD parts encyclopedia

Highly recommend getting new oem hose clamps as well. Makes the install so much easier.

 

just emailed him thanks.