NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   Engine Heat Problem (https://www.nopistons.com/1st-generation-specific-16/engine-heat-problem-39407/)

Hades12 05-24-2004 03:34 PM

My temp guage has been running at half or a little more for the last several weeks So far I have done the following



Bubble Check to see if an internal seal was bad> no bubbles.



Pulled all the air conditioning parts>thought it might be blocking air to the Rad.



Flushed the Rad with CLR> Flues look good and clean.



Cleaned the Rad outside> All the fins were very clean.



Changed the Coolent > replaced with distilled water and Water Wetter, and some antifreeze.



Double Alt Pully



16 Inch Electric Fan inside of the fan shroud.



Installed an aftermarked temp guage in the water pump housing.



180 degree thermostat, with a bypass hole drilled in it.



I took the car out last night and the temp guage got up to 210, This was in less then 5 miles and sitting at one stop light.





The water pump is not leaking but could it still be bad in some way?



The car is a 79 with a SP 12a, Webber 48 carb, and RB muffler.





Could I be running the car to lean? Should I adjust the carb to more rich?



Is 210 to hot?



Thanks for any help.

falcoln0014 05-24-2004 09:26 PM

Rotary engines run hot...just a fact of life https://www.nopistons.com/forums/pub...#>/biggrin.png



I'm still using the factory in dash guage and it runs about half way if its freezing...about half way if its 105 outside



if you havn't replaced the radiator yet i'd advise doing so...they do tend to clog up and or rot when they get old...my 84 factory radiator i what killed my first engine



Started slowly climbing up to the red...then it would bounce back down...and eventually it quit bouncing back...replaced the radiator and it started riding about half way from then on.



as for running the car richer or leaner...My car is running EXTREMLY rich right now...so I don't think making it richer would do much good...more gas = more fire = more heat



I'd watch that radiator...cost me over 200 bucks to get a good new one here locally when I finally replaced it...but i wouldn't be cruisin around the streets without it https://www.nopistons.com/forums/pub...R#>/tongue.png



and...even if you can flush water thru the radiator...that doesn't mean that the rows are clear...i've worked on 2 cars where the water flowed just fine...but almost every single row was clogged with stop leak...DO NOT put stop leak in your rad unless you're asking for trouble https://www.nopistons.com/forums/pub...#>/biggrin.png



replaced the radiators in both of them and bam...no more overheating

treceb 05-25-2004 07:10 AM

i always thought richer meant cooler...

also chek your oil, when was the last time u changed it?

supposedly my water pump is bad, it doesnt leak however, it just makes a lil whining noise and when it was taken out it would get stuck a bit when turned by hand.

83turbo 05-25-2004 07:50 AM

210 is kind of up there...You should be around 190 maybe. Just throwing this out - is your thermostat the right kind? It should have a springy thing at the bottom to block the bypass hole in the water pump.

Also water pumps are pretty reliable, but I replaced one once (not in a mazda) that had no impeller left whatsoever.



Richer does mean cooler - you can't burn the extra fuel without oxygen. The extra fuel cools it down. If you want to check your cruise mixture you might pull off the headers and look at the sleeve color, which might be more telling than the plugs.

Hades12 05-25-2004 08:23 AM


Originally Posted by treceb' date='May 25 2004, 12:10 PM
i always thought richer meant cooler...

also chek your oil, when was the last time u changed it?

supposedly my water pump is bad, it doesnt leak however, it just makes a lil whining noise and when it was taken out it would get stuck a bit when turned by hand.

Oil has about 400 miles on it.

Hades12 05-25-2004 08:25 AM


Originally Posted by 83turbo' date='May 25 2004, 12:50 PM
210 is kind of up there...You should be around 190 maybe. Just throwing this out - is your thermostat the right kind? It should have a springy thing at the bottom to block the bypass hole in the water pump.

Also water pumps are pretty reliable, but I replaced one once (not in a mazda) that had no impeller left whatsoever.



Richer does mean cooler - you can't burn the extra fuel without oxygen. The extra fuel cools it down. If you want to check your cruise mixture you might pull off the headers and look at the sleeve color, which might be more telling than the plugs.

The thermostat does have the thing at the bottom.



I need to find out how to richen the Webber now.



Would you happen to have any links on how to read the plugs.

83turbo 05-25-2004 09:20 AM

I'm assuming that you are running hot in "normal" driving, ie light loads. Basically your 12A won't run very lean under those conditions (I've been playing with a wideband). Due to the late exhaust closing, you get alot of unwanted exhaust holdover to the next cycle, which hinders combustion so you wind up running a sort of rich mixture for better ignitibility. Higher loads and higher RPM can run much leaner (drive fast - save fuel).



Does the car seem to run lean? (ie driveability problems, stumbles, "scratchiness")



If your plugs are white or a little green (copper burning from the electrodes), you're lean.



The weber has idle mixture screws at the very bottom. You can alter cruise mixture by changing idle jets. Main mixture is on the main jets plugged into the bottom of the emulsion tubes. What type of weber is it?

Hades12 05-25-2004 11:32 AM

48 Side Draft, Guess that makes it a DCOE?



It will stumble a bit around 1500 - 2500, But is just fine at anything above. I will try and put up a pic of it.





The only Carbs I have adjusted are on lawn mowers and my Tmaxx RC truck. Can I just give the idle jets a bit of a clockwise turn to add fuel? The idle and Main's are under the gold cap?

Hades12 05-25-2004 11:32 AM

Here

83turbo 05-25-2004 03:14 PM

Yes - idle and main are under the "mickey mouse hat". You can adjust the idle mixture screws (topmost in the pic) with a screwdriver, but the main and idle jets are sort of press-in things. When you remove the hat, you will see 4 screws (okay, so I'm referring to a Dell'Orto DHLA but it should be the same) - these are the jet holders. When you unscrew them, you will pull out the entire emulsion tube. Fuel jet is at the bottom, air jet is at the top - you have to pull off the jet holder to get to it if you are going to fiddle with those.

The brass screws to the left and right of "WEBER" hold the accelerator pump squirters.

I'm not sure what the others are - it's been a while.

To determine the cause of the 1500-2500 RPM hesitation, slowly tighten the idle speed adjustment screw, raising the idle. If it leans out and stalls, the idle fuel jets are too small (adjusting the screws won't help). If it continues to rev up okay, try different accelerator pump squirters. My Dell'Orto always seemed to have a problem there - I think because of the long, cold manifold.



Also I didn't see a cold start linkage in the pic. Do you have one?


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