Do they preform better than the stock pumps?

 

Ttt

 

Just run the stock waterpump. If electrics were the "rage" you'd have tons of guys running them, and that's just not the case.

I think you're looking at the right things. If you check your rad and it is NOT blocked, I don't know what else to tell you. Like yours, mine acted in a similar way. I didn't have coolant on my plugs either, but I think plug fouling comes later on when the breach in your o-ring is larger enough to allow a more substantial amount of coolant into your rotor housing. The danger in waiting for a longer period of time is RUST that will form from moisture in the housings. The pitting can ruin your plates, rotors and rotor housings. If your housings are still within spec, the cost of your rebuild will be substantially less by pulling it earlier, rather than later.

 

Thanks for the heads up.

I agree with you. If my radiator is not plugged I have no damn idea what is causing the overheating.

I have changed the t-stat, coolant lines, coolant flush, radiator cap, and now boil/flush the radiator.

I am still planning on building a shroud next weekend.

Would it possibly help any to change the angle of the way my radiator sits in the engine bay? I could probably swing the top side closer to the front bumper and maybe get 15 to 20 degrees of angle.

Other than that I have no idea what would be causing it to overheat.

I'm just stumped.
And I can't explain why the temps really only climb high when there is a load on the engine on the highway. It seems like you can run the **** out of it in town and it doesn't get near as hot as a gradule slope on the highway.

 

This is typical operation for an FD, especially when ambient temps reach over 90F. If you run them up a steady grade (i.e., 3 to 5 mile steady grade up a mountain pass), temps will rapidly climb. However, if you top the hill and your temps do not recover, you've got additional problems with your system.

That's why so many guys on this board who track their cars go to extreme measures to maximize their cooling systems (huge rads, monster oil coolers, sealing around the radiator, etc) and still most will admit to only being able to hot lap 'some' of their summer track sessions, and not all. Turbo rotaries are a frigg'in nuclear furnace and the problem is only exaccerbated when ambient temps get extreme this time of year.

 

In the linked thread below we had a long discussion on why a copper/brass CSF radiator would not cool my FD properly. The symptoms were somewhat similar to yours. It came down to the CSF rad needing more airflow to get enough heat transfer from the rad to the air than the OE (stock) rad.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/radiatorworld-com-radiator-assessment-660256/

This is not to dismiss the possibility that you have some other problem (like bad coolant seals), but may be food for thought.

 

Hey guys, I have been out of town for a couple of days.

I think that on the highway airflow may be a culprit.

I pulled my rad out last week to have it inspected and left it with my Dad up in North Dakota (he has the space and tools to actually work on the car).

He called me up on Wednesday and said no one in the area will boil/test radiators any more. So, I pretty much wasted a week.


On another note, I ordered the video from Atkins about rebuilding the 13B. Pretty cool video. It doesn't look super tough. The only thing I am concerned about is they really didnt go into discussion on what to check once the engine is disassembled. Like clearances, etc.

I think I could do the rebuild myself, but there are a couple of specialty tools that I would need. But I am concerned about opening it up and not knowing what to look for if there is more damage than just a coolant o-ring.

Where could a guy find more info about this?


This is the worst case scenerio. But, until I get the radiator checked/cleaned I don't want to think about a rebuild. But if the radiator is clean and there is no blockage and it still overheats it has to be an o-ring problem. Because from what I have seen so far, when the coolant expands into the overfill it doesn't want to cool and be sucked back into the engine. Talking to the guys at Atkins an o-ring failure could cause the coolant to be pushed into the overfill and not let it return, possibly causing the low coolant symptoms.

 

Ttt

 

Ttt

 

I just got off the phone with the radiator shop.

My Koyo checks out fine.

No leaks, flow is great, no forgein material during the flush.


What is my next option?

Replace the water pump?

Or is it definately my engine now?

 

checking the water pump would be my suggestion and it wouldnt cost a thing

 

I had similar issues. coolant test during cold didn't reveal leaks. Only when tested with the pressure tester connected as the car warmed up to full rated pressure did it show leaks. The leak occured during expansion of the sandwiched housing. 6 months later, it started slurping down coolants. 2nd engine that did this. I'm on my 3rd with Evans but I'm suspicious it's doing the same thing.

 

Since the rad and the thermostat check out, there are only a few things left, IMO, that could be causing the overheating problems - some of which you have surely looked at, but your saga is so long that I don't remember all of what you've said:

1. Air pockets in the cooling system due to:
a. Bad coolant seals
b. Something wrong with the coolant recovery system

2. Not enough air flow thru the rad due to:
a. Lack of sealing around rad
b. Aftermarket air ducts, etc., blocking air flow
c. No under-pan to direct air into and out of the rad

3. WP problem:
a. WP bad (quite unlikely, but costs little to check)
b. WP spinning backwards due to belt rerouting from stock (air pump removal, etc.)
c. Belt slipping on WP pulley, or pulley loose on shaft

 

Thanks for the reply.

1. a. I'm starting to lean this way, but I want to go through the entire system this weekend. We did a pressure test on a cold system, but I want to check it while its hot.

1. b. I just got a new rad cap (13 psi) and am going to also try that to see if the other cap (16psi) is possibly bad. The 16psi looks fine, but its worth trying.

2. a. After going thru the system I am building a duct this weekend so no air can escape.

3. a. I also don't think there is anything wrong with the water pump, I can't see any leaks, the belts are tight but not too tight, pully spins fine and is turning clockwise while looking at it.

 

What would cause the housings to expand, heat I'm guessing?

Shouldn't the motor bolts hold the housings together?

Is there kind of a "typical" place where it would leak if it was in fact the housings?

Thanks, Josh

 

Maybe this is your problem - IIRC the WP should turn CCW?

https://www.rx7club.com/showthread.p...+pump+rotation

 

I'm pretty sure everything is right.

This isn't my car, but I have the same Greddy pulley kit and the air pump removed.
My belts are running the same way.

 

I'm an idiot. Your correct. I don't know why I said "clockwise". It does in fact run "counter-clockwise".

Sorry for the confusion.

 

Ttt

 

Could your slower WP speed due to the larger pulley be a factor?

Dave

 

Maybe? I also have an underdrive pulley. It came on the car when I purchased it.

 

First thing you need to do the tests mentioned earlier in this thread to verify that you do or don't have an internal o-ring failure. An underdrive pulley won't cause any noticeable difference in temp control.

 

I've done the "champagne test" with no difinitive answer.

I've let the car sit overnight and pulled the leading plugs and turned the engine over by hand and not a drop of coolant came out of the plug holes. I even added a bottle of dye to the system and ran the car up to temp the night before to let it circulate throughout the engine.

Still can't find any leaks, although I am going to do a pressure test with the car running this weekend. Maybe as the car warms up the leak will be more evident.

I have replaced the t-stat, radiator hoses, coolant flush, radiator checked out OK, and I also picked up a new radiator cap.

I think I will also pull the water pump before putting everything back together just to check it over.

I've looked under the dash for signs of the heater core leaking, but didn't find anything.

Other than that I don't know what else to check.

As mentioned earlier I will fab up a radiator shroud this weekend.


Will a compression check show anything?

 

A compression test will not reveal a bad/damaged o-ring. The bubbles test is worthless, IMO.

The car should not have overheating problems in stock form. If you have to fab a radiator shroud to keep it running cool, then you have a different problem. I would suggest skipping the shrouds or other "extra" things to fix the problem as they should not be needed for a properly operating cooling system.

 

Thanks for the info.

What is your take on the AST elimination mod?

Do you think possibly getting something like the Pettit alum AST is better than just eliminating it?

I'm sure Mazda placed an AST on the car for a reason.

Would adding a new alum AST possibly have any difference?


How about the way the radiator sits? Right now it is completely vertical, but I do have some wiggle room and I could slant the radiator top towards the front bumper. Would this help any?


I should also mention that I did replace the belts on the car so I know the water pump belt is not slipping, but the Greddy pulley is a little polished.