okay, so. i'm prety much a rotary neophyte, armed with bits of information i glean from this great site.

anyway, i bought this 1989 GTU about a week ago. 7k on a rebuild, decent shape, i'm like 'lol awesome' and all that. fast forward to today. i go out and start the car and listen once again to little thing #1. the car will start fine and all, but while warming up, it'll rev and fall off, rev and fall, between about 1000 - 1400 rpm. after a few minutes of driving, it'll drop to a 750 rpm idle, but that's still unnerving.

SO. little thing #2. i'm driving to the reserve center and i notice the temp gauge going up. at the same time, the oil pressure gauge is just...sitting there, dead. i stop inside the gates and it hurns out the heater hose is cracked, so i bum a ride to advance auto parts and replace it, then top off the coolant. i thought everything would be fine, but not so much..

little thing #3-9orwhatever.i start the car, and it needs light pedal pressure to turn over. the idle thing comes back, only continuous and more peaked (900-1400!). the car feels like it's on its last leg, and i smell coolant again, so i stop and a peek under the hood reveals..pretty much nothing, but the coolant in the plastic jug by the right headlight (forgot name for it) is BOILING.

so i've shot this around town, and i've heard stuff like 'you need a thermostat' and 'check yer hoses for clogs' and 'water pump needs replacing'

i'm sorry if i overlooked any easy to find information, i'm just really distressed, and wanted an opinion from some of you guys before i limp it to the mazda dealership

 

This is critical... how long after you noticed the temperature gauge shooting up did you drive it? If you overheated it there is a good chance your newly rebuilt motor is fubared.

 

Yeah, the reving thing happens to my RX7 too, i have a rebuilt engine with about 5000km on it, it dosnt bother me, the car runs fantastic, but it would be nice to know what this is.

 

10 minutes, tops. i was a long way from home...

 

Did the gauge ever hit the "H" line?

What it sounds like to me: you lost some/all of your coolant, and when you filled it back up youd idn't follow the proper fill procedure, hence you have a lot of air still in your coolant system. The air expands faster than the water, when heated, so it's pushing all the water out.. you really do have to take care to fill these things properly.. Did you do the fill it up with the bleeder screw removed from the radiator, squeeze allt he hoses as much as you could, start the car and let it get up to normal operating temperature (~15 minutes at idle under no load). Once the water starts circulating, then top it off until it will take no more. It should now be full.

It is possible that you fubared your thermostat.. If you're concerned about it, or think it may be an issue,t hen go to a mazda dealer for an OEM thermostat.. there's been lots of people who have had problems with aftermarket ones..

I hope that those are your only problems.. .

 

The surging is more than likely due to a "bad" TPS or one that needs udjusting. You can search and find ALOT of TPS type info... It's a common problem and is a very simple fix (once you know what to do/look for).

I'd worry about the possible overheating/coolant problems etc... Now's probably a good time to replace ANY suspect hoses, thermostat replacement, coolant flush etc... Just to be on the safe side.

If I were you, I'd search around for 'blown coolant seals' or something like that, because there's also a lot of good reading regarding (that) subject.

Good luck,

 

#1 is a bad or mis-adjusted TPS
#2 is probably a disconnected oil pressure sender
#3 is probably a blown coolant seal- time to replace the motor.

 

i figured as much with the TPS.

i'll check out everything else come tomorrow, and hope i don't need another motor.