If your overheating problems did not show-up until 5000 miles after you did your cooling system mods then I'm starting to suspect that your problem has nothing to do with your mods. If the Fluidyne was new when you installed it then I really doubt it is clogged. Besides, aren't you saying that you've run the Fluidyne for 5000 miles without overheating?

 

jpandes - I'll certainly do the burp routine when I put it back together. Thanks for the suggestion!

 

Jonesboro - Only in the hot summer weather like in Sacto (which I see you are from too) it gets too hot. See my very first post for complete description of what it does. If you have an FD have you driven east on I-80 or 50 up the foothills/mtns on a hot day? What's your temps?

 

I've never had a temperature problem with my FD even on the hottest days in Sacramento. I've done most of the cooling systems mods that you have and I have 80K miles on the original engine.

Did the previous owner of your FD live in Sacto and if so have you tried talking to that person about temperature problems? If I understand correctly the way you have described your temperature problem it started occurring about one year ago and has progressively gotten worse. It sounds like you have eliminated all of the obvious issues with the cooling system. You did confirm that your radiator fans are operating correctly didn't you?

At some point you need to "preliminarily" conclude that the cooling system is operating correctly and open your mind to the possibility that the problem may be something going on with your engine/turbos that the cooling system cannot keep under control.

 

Well,

I've been cruising the forum reading anything to do with hot, temp, overheating, etc. Since I rebuild my motor.

I seem to have the same prob, same symptoms, etc. I haven't been sure if I should blame it on the Evan's coolant or not. After reading this thread, I'm convinced that I have a problem.

I'll have to think about it a bit, but if it's just Vaseline, couldn't I flush it out? Maybe I'll borrow a stock radiator and see how this performs.

James

 

RX7 8U's symptoms definitely sound like a clogged radiator, but his radiator was newly installed 5,000 miles ago and he's dealing with his original engine.

You guys with the recent engine rebuilds experiencing overheating problems should definitely consider whether or not your radiator may be clogged from rebuild sealants and stuff.

 

Here's a bit more info on my situation:

My car had a bad water seal. Nothing major, car was still drivable, but definitely needed fixing. I found a bargain ($400 shipped) on a new Fluidine and decided to go after it about 1000 miles before the rebuild. The thing was amazing. My temps rarely went over 200 (on city streets) unless I was in heavy traffic. Also, if I used the AC the temps were always 180-190, even in 100 degree weather and heavy traffic. OK, so maybe I could push it up to 220 if I drove up a large hill, full boost and AC on (100 degrees outside) but generally it took a lot of work to cross 200 degrees with the A/C on.

OK, jump to the motor rebuild. I back flushed (garden hose, after the motor was out) the heater core and radiator to remove all coolant and used a blow drier to force hot air through them in order to remove all of the water. After this, in went the motor and Evan's coolant.

Now, on a 100 degree day I can easily hit (city streets) 210-220 with the A/C on. Also, the car runs at 200-210 with the AC on the freeway at 70MPH. No AC on city streets is pretty much the same story … temps rarely drop below 200 unless I have a large hill to coast down. If I drive up a 3 minute (to the top) grade (more like a small hill) on the freeway with the A/C on (90-100 outside) the car will go over 230. I am using Evans, and have Viton water seals but it still makes me really nervous. Oh, and I'm talking no boost, easy driving.

I should also note that I've (per some threads on this forum) splash guard and added foam padding to seal the radiator's sides. There isn't anywhere for air to go except through the radiator.

So, anyone with Evans, A/C and a Fluidyne rad care to tell me this is normal? That is before I go switching with a stock radiator to compare.

 

I pretty much saw the same exact temps as you are seeing right after my rebuild. My stock sized copper radiator was not cooling much at all. I thought it was the EVANS coolant, which is supposed to run 10 F degreees hotter(but not boil over until 360 F @ 0 psi). I spoke to pineapple raciong, my motor builder, they said that I shouldn't worry about my temps until I see 260 F. Well I saw 250 F. Pineapple also said to check my timing. If my timing was off, it could easily cause excessivley high temps. Chuck from Rotary Extreme revied my datalogit settings and said that they were ok. I also burped my cooling system too.

After around 650 miles into breaking in my motor, I installed a Koyo($357.00 shipped from www.carradiator.com). I also had to pour in half a gallon more Evans coolant due to the bigger core. Now my temps are at least 20 F degrees cooler across the board:

On city streets stop lights and such: 88-89 C
On the freeway at 70-80 mph in the morning 65-75 F Ambient: 85 C w/ a/c on les with a/c off
Today 100+ F Ambient : 96 C w/ A/C on going up a freeway grade. I used to see 116 C w/o the a/c on this same road.

Get a new aluminum radiator. It worked for me.

 

Damn! Another $400 for a new radiator ... I may just go with the Koyo if this turns out to be the case ... I'll save a few $$$. Worst case, I can sell the Fluidyne if the new radiator doesn't do the job ... that is if there is nothing wrong with the Fluidyne.

Oh, mine is a Pineapple rebuild also ... Rob told me the same exact thing. I checked the timing, etc. out ... thanks for the info though.

 

So in other words, if you get a rebuild, get a stock radiator to catch all the stray engine sealant floating around in the cooling system, run it for a bit while carefully watching temps, then flush the thing and re-install your upgraded aluminum radiator that you just spent $400 hard-earned ducats on?

What does this "engine sealant" consist of?

 

It seems odd that all the people with cooling problems were using Fluidyne. I'm about to buy one myself. Maybe I should go Koyo? Do the Fulidyne use smaller water passages more prone to cloging? Who among us is the radiator expert?

 

Man Jonesboro is cruising Sac with the a/c on and cool engine temps and I'm sweating with a hot car. I'm really stumped. It must be my radiator. It looks fine on the outside and yes fans work fine too. Maybe it has crap in it or like I said before the welder had a bad day and took it out on the radiator core. I wish now I didn't chuck the stock radiator!

I'll pull the radiator out and take to a radiator shop tommorow and get it flushed/tested. Hopefully that will be the problem. I'll post an update later.

 

OK, I discussed this situation with my mechanic (he does a lot of rebuilds).

His answer was that there was no way that the vaseline and what not used in rebuilding a motor could clog a radiator. He says his experience is that whatever material gets in the cooling system ends up in the coolant overflow tank -- Vaseline does not mix with water and floats on top of it.

All that said, I'm still in the same boat as you, RX7 8U. Yesterday during the 95-100F day, I was hitting temps of 92-95C (on the PFC) during highway and city driving. This is with my fans coming on at 92C and WITHOUT the A/C on. My thermostat is only a couple of months old. I'm getting frustrated.

 

rynberg,

At some point you need to "preliminarily" conclude that the cooling system is operating correctly and open your mind to the possibility that your overheating problem may be something going on with your engine/turbos that the cooling system cannot keep under control.

 

Yes jonesboro that is the next step. I agree. To completely eliminate the cooling system though, I got the radiator out today and the shop I took it to doesn't do aluminum and didn't have a flush rig. So I bought some Prestone flush stuff, poured all of it in the radiator, filled it up with hot water, plugged the holes and shook it around to try and flush whatever is in there. Then I let it sit in the sun for a while and cook. When I poured out the water it was pretty cloudy. I then flushed it out with clean water. It is now real clean and with full pressure from the garden hose it flows all the water out the other end. So it's definitely not plugged up.

I also noticed the Fluidyne core has one row which has very wide but very narrow cooling jackets. Through the bottom inlet I tried to pass a .020" wire through it and it barely went through. So it wouldn't take much debris/scale to clogged this radiator up! Typical radiators have much wider jackets but you do get more cooling with this one I think since there is more cooling surface area for the volume of water in the radiator. The radiator only holds about 3 quarts!

So next step is get it back in the car, install the new water pump/t-stat and run the whole thing with 100% distilled water and more flush stuff. Then drain and re-fill again and see what happens.

 

Oh by the way check out what Fluidyne says about engine sealants:

http://fluidyne.netgarage.net/viewto...=136&forum=1&1

 

RX7 8U,

I fought an overheating problem with my daily driver (not RX7) for over one year so I know how frustrating it can be. Mine turned out to be a clogged radiator, also the last thing I checked.

You're doing everything right. You caught this problem before it destroyed your engine and your systematic approach is checking and eliminating the possible causes.

Hang in there. You obviously have faith in your abilities and workmanship. Although this is a headache for you now, I'm sure when it is all done and resolved you will look back on this as a valuable learning opportunity.

 

Thanks Joneboro. Hey its noon on a beautiful Sacto Saturday. What the heck are you doing inside on the computer? Me...babysitting my kid until my wife gets back so I can go back to work on the car......then tonight hit the sacto drag strip to see the jet powered dragster!

 

I agree, unfortunately....

 

I'm watching the Ohio State game on TV. (I grew up in Ohio).

 

I have a Fluidyne. It runs very cool. No problems of any kind.

By the way, I'm not the radiator expert.

 

I have a partially clogged stock sized raditor for someone local that wants to use it for a sealant catchers mit. You can have it for free. Just pick it up before the trash man does...

I wonder if the sealant can be flushed out?

 

Tyler,

Those temps aren't bad for 100 F degree days in the East Bay...

John

 

It's all back together now. Same hot coolant temps on a hot day in Sacto. Coolant was around 220F+ just driving around (a/c on) and not getting on it too much. Got on the freeway and it didn't really cooldown under 210 even after shutting down a/c. I pulled over to check the fans and they were running.

So I've done everything possible to the cooling system:
New waterpp, new t-stat, removed and flushed fluidyne radiator, flushed whole system twice with distilled water and Prestone superflush, refilled with 30% coolant, a bottle of waterwetter and distilled water. I bled the system too by removing the TB line. It's full and no leaks.

Also checked the fans. They come on around 225 so the Miata switch I have doesn't come on at 207 but I read a post that said the later model FDs the fans still come on at 225 even with that switch. So I guess that's what I got. But fans work fine otherwise.

So as Jonesboro suggested it must be something else. I have no idea what it could be. It runs great otherwise. Good boost, good power, doesn't smoke, good idle. It just doesn't like hot weather.

I'm driving up 50 to Carson City area early tommorow morning so we'll see what happens......

 

Greg, you asked me for some temp readings in hot weather. I got some today coming back from the Marina Autocross.

I was on hwy 101, north of Paso Robles. Driving 80-85 mph on mostly flat terrain. Outside temp around 100 degrees. With no fans, and no AC, the temps stayed betweeen 190 & 195. With the AC on, temps went up a couple of degrees, but did not reach 200.

Maybe if you started driving without your foot on the brake, all the time, the car would run cooler