FC Rotory Help

ecam8000 · Postby **ecam8000** » Sun Apr 17, 2011 9:14

I had to take my trailer to rescue Christi's RX7. At my house, we dropped the coolant and I pulled the T-stat. Test in hot water (near boil) and T-stat opened. Installed and refilled ran engine to temp. T-stat opened and fan came on, idle steady gauge in middle of normal range. She test drove to heat it up, temp still normal but engine hunting for idle. Runs a few seconds around 700 then drops to 400 ish near stall then picks back up to 700. Pulled plastic 90 to look in throttle body - very clean. Idle (air bleed) screw on top off t-body backed out to top. Any ajustment in and the idle drops. Car does not want to restart while hot.

Alright Rotory Guru's what do I look for next? It does seem the temp issue is due to a inefficient radiator (no coolant loss) or is it due to tune (lean)?

alex_n/a · Postby **alex_n/a** » Sun Apr 17, 2011 9:14

this thread describes the problems but no clear answers. It will most likely be leaky injectors or bad throttle body.

http://www.nopistons.com/forums/topic/29622-hot-start-issues/

christi · Postby **christi** » Sun Apr 17, 2011 9:14

Not to mention when I drove it around whether hard or cruising after 20 mins the car became extremely hot, by the time I got Eric's driveway it turned off (not by over heating but by idle died below 400rpm). After the car shut down it was still above boiling temp, after doing everything stated above..

I want to know if any of you gurus would be interested in going to eric's 04/23/10 to work on the car, find out additional info/tune up something? It doesn't make sense as to why it's overheating and not leaking. Possible radiator?

Sent from my iPhone.

iani1.1 · Postby **iani1.1** » Sun Apr 17, 2011 9:14

sounds like the air bypass relay is out. its located at the passenger side behind the headlight

chickenwafer · Postby **chickenwafer** » Mon Apr 18, 2011 9:14

It may be worth it to get a coolant system pressure tester to ensure there isn't any leak. Otherwise you could have a blocked up radiator, bad water pump (although the FC water pump is pretty robust), etc.

Postby **RX-7 Chris** » Mon Apr 18, 2011 9:14

here is a good place to start: http://foxed.ca/foxed/index.php?page=rx7manual

ecam8000 · Postby **ecam8000** » Mon Apr 18, 2011 9:14

chickenwafer wrote:It may be worth it to get a coolant system pressure tester to ensure there isn't any leak. Otherwise you could have a blocked up radiator, bad water pump (although the FC water pump is pretty robust), etc.

I have the tester, she did a water pump Saturday. Next chance I'll have is Wednesday, I'm going to try a different T-stat and rad. cap. I'll do a pressure test then. Hot shut down causes a "coolant flash" and sends it past cap to reservior, half hour later the coolant is pulled back into radiator. I'm sure there is air in system after that happens.

ecam8000 · Postby **ecam8000** » Mon Apr 18, 2011 9:14

RX-7 Chris wrote:here is a good place to start: http://foxed.ca/foxed/index.php?page=rx7manual

Great link Chris! Now get a helmet.

iani1.1 · Postby **iani1.1** » Mon Apr 18, 2011 9:14

i dont think the problem has nothing to do with the cooling system. it might be that the engine is leaning out due to the bad or not working relay or maybe tstat mazda was anal about using the oem tstat and having it set at the right direction

also in a rotary it doesnt really matter if there is air in the system, it usually bleeds itself after a little bit through the overfill.

chickenwafer · Postby **chickenwafer** » Mon Apr 18, 2011 9:14

I disagree about air in the system. When I installed an aftermarket radiator in my old RX-8 I was overheating and couldn't figure out why. That's when I picked up the Lisle funnel and hooked it up and BURP! Huge air bubble came out and no more overheating. Any sealed pressurized coolant system is susceptible to an air pocket. It's impossible for air to bleed off in a pressurized system.

That being said, I'm not convinced it's the issue christi is having.

Postby **RX-7 Chris** » Mon Apr 18, 2011 9:14

Christi, Did you ever fix the things I said needed to be done after I looked at it?

Replace the water pump, remove the air control valve and install and air control block-off plate.

When I looked at it, the smog pump was removed and the air control valve was just dumping exhaust into the engine bay. Also the water pump was leaking through weep hole.

iani1.1 · Postby **iani1.1** » Mon Apr 18, 2011 9:14

chickenwafer wrote:That being said, I'm not convinced it's the issue christi is having.

well see<_<... if they ever figure it out

oh yea ill add some useful info
http://www.rx7club.com/showthread.php?t=681471&page=1

christi · Postby **christi** » Mon Apr 18, 2011 9:14

Chris - water pump was replaced Saturday night. Block off plate no - temp yes but I'd like to purchase the one you pm'd me about.
Sorry this may be stupid queruon, but where is the ACV?

Do you think it's a pocket of airthat we've yet to get out then?

Sorry for no replies still at work, an it's busy

christi · Postby **christi** » Wed Apr 20, 2011 9:14

So, if I replace the radiator, do you think that this *may* solve my issue, if .. replacing the radiator cap and fully airing out the system doesn't?

I'm already planning on doing a rebuild probably end of this summer, I have a feeling my compression is *extremely* low, to begin with....

ecam8000 · Postby **ecam8000** » Thu Apr 21, 2011 9:14

Christi, I doubt the compression is low but we can check it if I can find my tester. Low compression leads to bad idle and poor power. I don't see the connection with overheating. I need a rotory guy to chime in with what compression should be for one of these things, and do I check leading or trailing or both? We will try the new T-stat and rad cap, and I hope to measure actual temperature of the coolant compared to gauge on dash. If the temp continues to rise when running, it points to cooling system not getting rid of heat fast enough (plugged radiator, inadequate air flow from electric fan) or a poor tune causing the engine to run lean. I am not a rotory tuning guru, but we will see what we can come up with. Anybody who wants to come and help is welcome.

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