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I have a 93 touring, that I drive a few times a week with no issues. Driven the car both on the highway and in heavy traffic in 95* weather and have never had an issue with the car overheating. I know the radiator fans work, because I can hear them running after shutting the car down and putting the key in the ON position after it has been thoroughly driven.
The car has an aluminum fluidyne radiator that is maybe a year or two old, an aluminum ast with a 16psi stant cap, and a catless downpipe. Other than that it is pretty much stock. It also has an OEM mazda crate rew that was installed less than 10k miles ago. No issues with smoking and the car was very meticulously maintained by the previous owner.
Today, I decided to go to a local cars and coffee meet. I started the car in my garage and let it idle for 3-5 minutes, and left. I got maybe 5 minutes from my house and I noticed the temperature needle begin to rise. I immediately cut the car off, pulled over, and opened my hood. When I put the key back in the ignition in the ON position, the temp needle stays in the middle position. The radiator does not feel hot. It’s warm, but I can touch it without discomfort, and the engine bay does not seem to be radiating excessive heat. Everything is touchable without burning my hand.
Not really sure where to go from here. I may just wait until the car cools down completely, baby it back to my house, then change the radiator cap, thermostat, and flush/burp the cooling system. Any ideas as to why this may be happening are greatly appreciated
EDIT: Also want to add that the radiator fans were not on when I cut the car off after noticing the needle rising. The needle also never reached the white mark, as soon as I saw it above the half way point, I turned it off.
i when its cold, crack the filler cap and radiator cap and make sure its full, sounds like an air bubble. the other thing is to make sure the radiator cap is clean and the flange it seals on is clean, i've seen cars that had some grit on the cap that acted like blown coolant seals
i when its cold, crack the filler cap and radiator cap and make sure its full, sounds like an air bubble. the other thing is to make sure the radiator cap is clean and the flange it seals on is clean, i've seen cars that had some grit on the cap that acted like blown coolant seals
I just cracked the filler cap and the cap on the ast, and both did not have a visible coolant level in it. However, the overflow tank is full. Car is pretty much cold now, so I think I’m going to try and get her home asap
I just got the car home, needle slowly crept back up to operating temp, and didn’t move from there. Granted it was only a 3-5 minute drive. After the car cools back down, I’m going to start tearing into it. I assume I can/should only get a radiator cap and thermostat oem from mazda?
Did some more research, I’ll also be installing an FC thermoswitch and may look into drilling the oem thermostat. I’m still looking for some feedback on my situation though, I’m hoping the car didn’t get hot enough to hurt something. I will update once I’ve changed all the components and flushed the cooling system, and have taken the car for a drive.
I just cracked the filler cap and the cap on the ast, and both did not have a visible coolant level in it. However, the overflow tank is full. Car is pretty much cold now, so I think I’m going to try and get her home asap
if there is a leak somewhere, that is the symptom. the coolant gets pushed out to the coolant tank, but because of the leak it can't pull a vacuum to pull the coolant back in.
Hmm alright. I haven’t had any issues with the low coolant buzzer coming on. The car was also in storage for about 2 years before I picked it up, and I don’t know that the coolant was flushed or changed after that. I just picked up some distilled water and an aluminum safe coolant system cleaner. I’ll be flushing out all of the old coolant until it runs clear, and refilling it with a 70/30 mix. I’ll also rent a pressure tester and pressurize the system, and try to find a leak to the best of my ability.
When you go to refill the coolant, do yourself a big favor and get a lisle funnel. It makes life a lot easier. You can also pull the coolant hose off the back of the throttle body ( the one that goes to the rear iron) while filling until you get some coolant peeing out. That helps bleed most of the air out and makes the rest painless.
Coolant that came out of the car was gross, had a ton of rust in it. I filled and drained the system 4-5 times until the water ran clear, then I filled it again, and ran the car with the heat on full blast to circulate the new distilled water. Noticed that my heat wasn’t blowing hot at all. Lukewarm at best. I’m going to drain the coolant once more, and refill it with distilled water and add the cooling system cleaner. Then I’ll drive it for a couple days to get the 3-6 hour run time specified by the cleaner to get all the mineral deposits out. Drain it once more, and refill it with a fresh coolant and water mixture. Will update accordingly
Make sure you're removing the block drain plug on the center iron. Its the lowest point and when it comes to getting the sediments and things out, that's your best best.
Make sure you're removing the block drain plug on the center iron. Its the lowest point and when it comes to getting the sediments and things out, that's your best best.
Thanks for the tip. I made sure to remove the plug out of the center iron every time I flushed it. Just drove the car at low speed around a parking lot for about 20 minutes, making sure to spend time idling and getting into boost a little bit. Temp didn’t seem to budge. Also blasted the heat for a bit too, to get it to circulate through the heater core. I was mistaken in my previous comment where I said I didn’t think the heat was working. I read some other threads and learned that the heat is not plumbed through the vents that blow towards you
Sounds like you've got it covered. One thing I thought of at first is the thermostat - parts store thermostats are JUNK, have seen many fail within a month or two. Mazda OEM period on thermostats.
Sounds like you've got it covered. One thing I thought of at first is the thermostat - parts store thermostats are JUNK, have seen many fail within a month or two. Mazda OEM period on thermostats.
So I’m bleeding the coolant, and I start the car with the funnel on and I get this white foam. Not milky or oily, just foamy. I did put some prestone cooling system cleaner in. Could it be that? I’ve never seen anything like this before.
Replaced the ast cap, and now when I pressurize the system using the pressure tester, I’m getting coolant pissing out of the overflow
Edit: I’m actually still hearing some air leak from the new ast cap. The system doesn’t want to hold more than 10-12psi, and I hear the overflow bubble when pressurizing it above 10psi. Then it slowly leaks back down to around 10psi. I’m pretty sure the ast I have is the Pettit Racing ast (came installed in the car). I’ve read about some people having issues with them failing. Could this be causing my issue? There don’t seem to be any other companies manufacturing an aluminum ast nowadays
Left the pressure in the system all night. Found that the pressure had dropped to 7.5psi overnight. Somewhere, there is something not sealing properly. Could this be enough of a leak to cause the system not to pull enough vacuum to draw coolant back in from the overflow? My gut tells me it's either the AST itself or the cap that I got. To rule out the cap that I got (Stant equivalent from the parts store) I'm going to return it and order a new cap form Pettit racing that is confirmed to fit their AST. While that ships, I'm probably going to drain the coolant once again and pull the whole cooling system out to check for leaks in any of the lines or hoses. It could probably use a good cleaning anyway. Not sure that the detergent was enough, there was quite a bit of rust in it as you can see from the pictures. I also removed the cold side intercooler piping from the car last night and discovered some oil in the charge pipe, so while I'm removing the cooling components, I may as well remove the intercooler and charge pipes and give those a good cleaning too.
Any additional advice or information is appreciated.
A leak like this could be caused by almost invisible pitting in the seat area for the cap seal. Any slight irregularities there might allow it to seal at low coolant pressure, but higher pressure could cause the seal to pull away just enough to allow slight leakage.
Also, on my Pettit AST, use of the lever on the "lever-pressure-release" cap caused the seal to be pulled off center just enough to prevent it from sealing properly. I disabled that feature, and that cap now works as it should.
The foam is most likely from the Prestone flush. You may want to flush more clear water through the system and get all that out then fill with regular antifreeze/water mix.
The Pettit AST's are kind of crap. I've never been pleased with them. Either look at AST elimination or get a better one. I think that's going to be the root of a lot of those problems, even if you half way fix it now it's going to bite you again down the road.
Hmmm okay. I’m going to try pressure testing the system through the ast to try and rule out any issues I may be having with the relief spring cap sealing. I don’t particularly want to delete the ast, so I’ll either look into replacing it or cutting the neck off and welding a new one on myself. But before I go ripping things apart, I’ll pressure test it using the ast to make sure I don’t have any leaks in the system besides the cap.
Am I correct in assuming the system should hold 16psi when pressure testing it through the filler neck with the 16psi cap on the ast?
08-28-21, 09:17 AM
