Finally back to it.

I've replaced the front and rear rotors, shoes, shocks, struts, and front stabilzer linkage.

I finally got it back on the road. Prior to doing the above I replaced the thermostat and the water pump. The car was, and is still, overheating.

I drove it back from the mech. today; about 3 mi. Everything was fine until a few blocks from home, when the car temp started to rise.

A fella came by the other day; said he was having similar problems with his; no overheating on the freeway, and no overheating in low gear and under 30 mph. But, anything else overheats everytime.

The guy said it was his fan clutch. He says he replaced the fan clutch and the problem went away..

Thoughts about any or all of this?

 

Here's a September 15th thread that describes how to test for a seized fan clutch: https://www.rx7club.com/1st-generati...-time-1147356/ Your theory is that you might have a clutch that never engages even when hot, so look at the test method. Then see if you are free wheeling when it should be engaged.


My advice is that if you read the 1st gen forums, you will come across these things. When I got my recent FB in 2010, I was certainly mechanically inclined, but had no thorough knowledge of the car, These forums are an absolute treasure and the people here are tireless in helping out (as you have seen!).

For searching, I find the site's search box is okay, but I am most comfortable when I search using Google's scan of this specific site, for example put this into a Google search bar:

site:https://www.rx7club.com/1st-generation-specific-1979-1985-18/ "fan clutch"

Note the bolded items. This tells Google to search only these 1st gen forums for the exact term "fan clutch".

 

Thanks for the link.

I read through everything and watched the video.

Went out to the car:
1. Fan free spins by hand when car is off
2. Fan starts and spins when car is started
3. I can stop the fan spin, with a "broom", while the vehicle is running and continues to spin once broom is clear
4. I let the car run through choke and for 10 min.

I've provided a pic of the temp. gauge and its position after 10 min. at ideal.

Thoughts?

 

Like I said, the test in the thread I linked is to see if the clutch is seized, not if it just free-wheels always, which is what you are interested in knowing.

The following is all based on reading forum posts:The fan clutch works by "engaging" when the *body of the clutch itself* heats up, the fluid (that's supposed to be inside the clutch housing) thickens with heat, causing the fan to turn with more engagement.

Note that while you're temperature gauge is reading the coolant temp, it is not reading the fan clutch body temp. Also, it is a fluid clutch, not a directly engaged mechanical link. Even if it's warm enough to engage firmly at some thousands of rpms, you would still be able to move the fan by hand when the engine is off.

Because of all of the posts here on the subject, I went out and tested my fan. My cooling system is working great.

When the fan clutch body is cold and engine idling at ~750, I can easily stop the fan's rotation with the bristles of a brush, here I recreated the video test from the other thread.


I then drove around for 5 minutes at 35 MPH in 2nd = 4-5K RPM sustained. My coolant temp gauge went from 1/3rd to about 2/5th's of scale, engine bay hotter, and fan clutch body noticeably hotter to the touch. I could not stop the fan with the bristles, but I could slow it a bit.

 

Still wrestling with the overheat...

I've been working it from the inside in to this point.

Coolant pressure test revealed an audible slow leak / pressurized release - sounded like something frying.

Car overheats in stop and go. Haven't had it on thr freeway; however, the temp seems more stable during extended stretches under 30.

When I did the coolant test through the radiator cap I could definitely hear what sounded like air forcing itself through a tight space.

I never saw any fluid on the ground - though a slight fluid leak could have been consumed by the hot metal around it.

I've checked the hoses, overflow, did the broom test on the fan, replaced the thermostat and the water pump.

Watched a video that talked about a block tester kit. Will this work on my FB to confirm whether an exhaust leak into the coolant system is the cause of the overheating?

Is the fact that I could 'hear' a leak mean its not an exhaust issue?

 

maybe the radiator is blocked. remove radiator cap, run engine until it is warmed up, droplets of water will evaporate quickly when squirted on the block when it is warmed up, radiator flow should be very turbulent. and check the front of the radiator for leaves and plastic shopping bags.

 

Finally back at it.

Found out the fan clutch and the radiator (30 degrees hotter on the bottom than the top), are bad.

Where can I get both?

I called Autozone, they said their system doesn't even show the 84 FB equipped with a fan clutch...what?

 

Didn't you buy 2 FB's? What about the other one?

 

What can I tell ya...I'm undecided🤣

I've already put other new parts under the hood; why stop now. Especially for this.

I've got a Mazda guru that's gonna set aside time in a month to look over the 85.

Might come outta this with two running FBs that are in good shape.

I've always been a fan of keeping as many running and stunning as possible.👍🏾🤙🏾