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Uh Oh, Sort of overheated...

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Old 09-20-04, 02:33 PM
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What's an RX-7 ?

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Uh Oh, Sort of overheated...

Well Im not too sure if anything is hurt but my thermostat stuck open last night and I blew a coolant hose off of the drivers side while on the freeway. The weird part is my coolant buzzer came on but my PFC only rose up to 99c. But the stock temp gauge sky rocketed instantly to the top.
I towed the car home and looked at it this morning and filled the coolant back up, reconnected the coolant hose that blew off and started it up. It started perfectly as usual and the thermostat appeared to be working properly now but for a while even after it was warmed up my idle was up to 1600rpm at about 82c on the commander and the stock gauge was reading normal. Then after a few more minutes it hesitantly dropped back down to 900rpm where I have it set.
One thing I did notice is it seems like its smoking a little more than usual, but it doesnt smell like coolant at all. I know the seals on my turbos are going bad but it seems more smoke than usual is coming out...?
Anybody got any feedback on whether or not im "ok", it seems fine to me but im not sure... Maybe just paranoid, my motor only has about 12k on it...
Old 09-20-04, 03:04 PM
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should be ok as long as you shut it down ASAP ! ? !
Old 09-20-04, 03:16 PM
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Maybe the added heat just made my turbos a little bit worse than they were, The motor sounds good and strong but I wont be able to drive it around until later tonite after I put a new thermostat in and stuff. And there isnt any coolant or anything else in the oil so thats good. Maybe I got lucky...?!
Old 09-20-04, 03:56 PM
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I think this car is pretty good at letting you know when something is wrong...
Old 09-21-04, 10:20 AM
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Well I put the new thermostat in and a new hose clamp on the coolant line that blew. Its seems to be cooling pretty good again but Im still a little concerned about the coolant seals maybe being damaged. Are there any ways to test this or things that I should be looking for potential problems ?
Old 09-21-04, 11:05 AM
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TwinTriangles, did you find out why your pfc only showed 99c for water temp when this occurred?
Old 09-21-04, 12:21 PM
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I dunno, Is there more than one temp sensor, Theres the one on the block on the drivers side. I was thinking maybe the pfc reads from a different one and since the whole coolant line blew off the PFC was basically just reading the steam in the engine and the stock gauge was reading actual block temp. ? But Ive seen 99c on the commander many times and the stock gauge was nowhere near the H...
Old 09-21-04, 12:56 PM
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lucky...
Old 09-21-04, 01:35 PM
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Originally Posted by TwinTriangles
I dunno, Is there more than one temp sensor, Theres the one on the block on the drivers side. I was thinking maybe the pfc reads from a different one and since the whole coolant line blew off the PFC was basically just reading the steam in the engine and the stock gauge was reading actual block temp. ? But Ive seen 99c on the commander many times and the stock gauge was nowhere near the H...
There are several water temp sensors on the car. The one the PFC was reading from is most likely the one on the back of the thermostat housing (the green connector). There is also one on the block that the temp gauge reads from. There is also the fan relay sensor/switch (also located on the back of the thermostat housing.)

-bill
Old 09-21-04, 01:44 PM
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Your PFC probably reported a low temperature because it gets its input from the coolant temp sensor, and if your coolant all leaks out, you are basically then measuring air temp which will be lower. The stock temp gauge works off of a sensor in the block on the driver's side and reports the temp of the block metal.
Old 09-21-04, 03:58 PM
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What's an RX-7 ?

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Well the stock gauge blew up to the H in about 1 second, Im gonna finish burping the coolant system and then maybe try the champagne test and/or get a pressure test...
Old 09-21-04, 04:20 PM
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TwinTriangles,

Few things I found might help you with your situation.

Couple of months ago, I finally lost my engine due to coolant seal failure.

Last Sunday, I finally tore my engine down and saw the faulty seal.... and the many pitting surrounding the seal.

Just to let you know, I didn't know this but my engine seemed to be rebuild. As turbos seemed to have less than 20K (by exhaust manifold, apex seals and housings).. I've also purchased couple of engines that lost its coolant seal and I saw the same thing.. pittings on the plates.

My sympton was very similar to yours.. i over heated mildly (99-103C) few times and went away.. and few months later, it shot up to 113C and went away.. and finally hit 125C...

Just as my engine builder told me from day one when I broght my spare engine to him.. Its seems to be very important to lap your plates before assembling.. I didn't know how important that was until I start seeing small pits.. which I thought how can that cause coolant seal failure.. but I've now seen at least 3 engines of my own with all around 25K or less with exact same problem, I'm starting to realize what my builder was saying.. So, if your current engine is rebuilt and previous problem was coolant failure, I'm guessing you'll have the same problem.. As your builder probably didn't lap the housings and just slapped it together.. I really couldn't see any of these pits until my builder lapped for around 10-15 minutes.... He tested me by asking me if I saw any pits.. I looked for about 3-4 minutes, didn't see it.. Until he lap it and all the small dust size pits showed up.. And realized how could an engine builder without a lapping table could see such a pitting with out lapping?? which was the point that he was trying to make.... which definitely convinced me!!!

Hope this info might be useful to those whom are considering rebuilding their engine or getting a reman..... as two failed engines I purchased were Mazda reman with their serial number plate was still on..
Old 09-21-04, 04:31 PM
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Oh, Thats great inormation, I have no idea how Pettit does it, Ive never actually heard of lapping the housings before but I would assume Pettit would do that. Im not really trusting this whole champagne test either the more I read about it, I think I'll just pressure test instead, seems a more sure way to do it.
Old 09-21-04, 11:14 PM
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The champagne test works to determine if your engine is toast or not.. Pressure test will determine if you have coolant leak.. but that could be anything other than coolant seal leak.. I recommend doing both.. Good luck!
Old 09-22-04, 12:12 AM
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Im not really to sure what to think about this but I just finished completely burping the system, did the champagne test and no champagne bubbles here. But my car will not cool, it heats up pretty fast and when I turn my fans on high I can hold it at about 94c, thats just idling, it never used to heat up like that at idle. I havent driven it aroung much yet to see if it is consuming any amount of coolant or anything, but generally before this I would really have to be beating on the car or just cruising on a super hot day, never was it not able to cool itself down at idle with the fans on high...
Old 09-22-04, 01:06 AM
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Maybe now you have a different mix of coolant/water?
Old 09-22-04, 08:47 AM
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Try this..

let your car completely cool down.. Say overnight..

Next day, fill up your coolant system thru the filler neck.
Leave the filler cap off and ask someone to crank the car for you.

If your coolant starts to overflow, right after crank or few seconds after crank, then your coolant seal is toast. If it starts to over flow minutes after (2-3) I say you might have air pockets... It does take awhile to get all the air out of the system..

Good luck once again!
Old 09-22-04, 10:27 AM
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What's an RX-7 ?

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Thanks for your help Herblenny, I tried that this morning and it took like about 1-2 minutes before it started to spill over, No champagne bubbles still, Im going to drive it around for a while today and see if I notice at all that my coolant is disappearing or anything else.
Old 09-22-04, 11:35 AM
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Originally Posted by TwinTriangles
Thanks for your help Herblenny, I tried that this morning and it took like about 1-2 minutes before it started to spill over, No champagne bubbles still, Im going to drive it around for a while today and see if I notice at all that my coolant is disappearing or anything else.
Hmm.. I'm slightly worried that it spilled over in 1-2 minutes.. I'd tried this same thing on a friends car and it was still for minutes (4-5).. and just shut it down..

When cool, open the filler cap and ast cap and fill it to the top w/ coolant, start and let it warm up to 86-93 range, shut it, and repeat the process.. after doing this for 2-3 times and still spill over, than I say you might have a small coolant seal leak..

Gook luck!

PHIL
Old 09-22-04, 12:15 PM
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I drove it to work today and it still feels like its not cooling properly, Generally no matter cruising or idling or boosting when it heats up to about 92c I flip the fans on high and in about 2minutes it would cool all the way down to 83-84c, its cooling but not that far or fast.

I let it heat up to 92c as usual then flipped on the fans, Cruising the freeway at about 60mph it didnt start to cool down for like 5miles, then another five miles of side street driving when I pulled into work it had brought it down to 87c, Maybe thats just due to the new thermostat working propertly and the one before wasnt working properly and would heat up and cool it down much faster than the new properly functioning one?
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