I know its like winter out there, but my car never seems to warm up.. no matter how long or hard I drive.

Its about 6 degrees C outside and I just drove home before, about 20 minute drive, I'd run the car only 1.5 hours before, so I let it warm up around 1500rpm for a few mins then got on my way, kept below 3500rpm for the first 10-15 mins.. then started taking it a bit further...

Well the needle never left here:


Now this is the same during the day too, in the sun, about 16 degrees out... and the needle still only came up to here.

I ripped my spark plugs out which are about 4 months old and they were pretty black and brown, this has me thinking im running rather rich... There is also a long patch about 80cm long on my drive behind the exhaust which is all black from warming my car up in the mornings...

1982 with a 3 core radiator, 13B S4 engine (6 port and mods below)...


just wondering what you guys think... is it normal that it is running this cold? I remember a few months ago that it used to usually sit around a quarter... now it barely gets off the lowest mark. are there disadvantages from running this cold?

Cheers and thanks in advance,

Paul.

 

What temp sensor are you using?

 

well first things first I would check that the sensor is still intact... it will get hotter then that even if its rich it doesnt make much of a difference. To me it sounds like your sensor wire fell off or something making the temp gauge not move...

 

Try a different sending unit. if the result is the same, If I were you, I will install put a "T" on the heater hose and install a mechanical water temp gauge for a peace of mind.

 

The gauge does move though and it comes up real slow.. just doesnt come up as high as it would in the past...

Could this be a thermostat problem? maybe its letting water through too fast?

 

i know this may be off subject, but whered you get your 3 core radiator at?

 

first, are you running a e-fan or stock. fan should be off til it gets hot say mid-level. now with the t-stat or having no t-stat, the stock temp should move higher than that. its hard to troubleshoot when there isnt sufficient info on your set up.

 

sorry, its the stock clutch fan. no efan.

regarding the 3core it was on the car when i bought it.

with the clutch fan from memory whenever i bring the revs up, it spins up too... at all times.. is it normal to always spin up faster with more revs, or should it be at a very low speed at all times when the engine is cold? any easy tests?

 

With my experience running no t-stat, the water temp should be higher than that as in the picture below. thats after an hour of driving on the freeway. Im running a HE 3-row radiator (more fins than the usual mail order stuff but approx $50 more), no t-stat and 50/50 mixture of antifreeze.

Clean the sending unit as well as the male/bullet electrical connection. if that doesnt help, then try a different sender OR install a mechanical gauge (stay off those cheap *** autogage and sunpro with unsealed t-couple).

 

im guessing my tstat could be jammed open because the manual here says its meant to open at 82 degrees C, and that would be about halfway up on the gauge there...

Ill pull the sensor and clean it, clean contacts and pull the tstat and have a look at it tomorrow morning. Anything else I should do?

edit: and ill look into testing the clutch fan... because since you run without a tstat warmer, something gotta be wrong here :P

 

get a thermometer take your t-stat out and put them in pot with hot water, check if its openning and shutting at the proper temps. sounds like your t-stat is stuck open. I would just change it.

 

ill test it out tomorrow morning too, cheers. Thanks everyone for your tips.

 

It definately sounds like the thermostat to me. My car has ate 2 in the past 6 months, stick to the Mazda OEM ones. When I ran without a thermostat since mine messed up, the car wasn't warming up, it was stuck around 50 celsius. After I changed the thermostat, everything worked fine again.

 

Guess what?! There was no thermostat!


I'm embarrased to have not noticed this earlier... I guess in summer its better to run without one? This is probably the coldest weather this car has seen in a long time..

It's running at a nicer temperature now, although its about 8 degrees C outside (which really helps keep things cool) - when I accelerate the temp gauge goes down instantly, as the cold air is pushed through the radiator.



I wasn't able to get a mazda thermostat, so hopefully the one I picked up to suit an '88 rx7' - which is approximately what my engine is, will do the trick.

Cheers for all the help and ideas!!

Paul.

 

my 74 repu had no tstat when i got it, it just took a long time to warm up, but never had a problem actually getting to temp, and i got it in winter too

 

I guess mine was having difficulty warming up because of the larger than stock radiator, plus I have removed the AC Radiator so it flows even better.. in summer it was running fine without the tstat.

 

how many rows are you using? The most you can put on a stock RX radiator is 3-row.

 

3 rows it is.

 

Looks like the Recycle port has been blocked.

 

Good point alot of people just simply remove the thermostat and don't block the recycle port. You get an inaccurate temperature read when that port is left unblocked with no thermostat. Your engine temperature will actually be higher than what the sensor shows. Since the recycle port is blocked a simple solution for you is get an old thermostat and gut it out. It will be enough of a restriction to get your engine up to operating temps and still flow good to keep things cool on hotter days.

 

What does the recycle port do and where is it exactly? And I'm guessing this is why my engine sounds a bit different now with the thermostat in there?

Is it possible to unblock it? Would it be a better idea to leave it blocked and have a gutted thermostat in winter / no thermostat in summer? Or should I unblock it and have a normal thermostat?

Are there performance advantages from having no thermostat? Less resistance on the water pump?

Sorry about all the questions but I really want to learn all this stuff

Another picture if it helps with explanations:


TIA

 

See in that picture where there appears to be a brass plug well that is the recycle port. If you think of the system when the thermostat is closed the 1/2in hole is open and allows for hot coolant to recirculate into the engine to speed up warm up. Now when the thermostat opens it closes that hole and forces all the hot coolant out the engine and go to your radiator to be cooled off. Now if that hole is left open the whole time you have to remember that the pressure from the water pump is going to force "cool" coolant through that hole and give you a false reading of temperature. Think of where your temperature sensor is at it is right below the thermostat and right above that 1/2 hole. So you are getting a cool reading at the sensor but the actual temperature in your engine will be higher. Hope that makes sense to you. Since someone already plugged that hole I wouldn't worry to much but if you put a thermostat back in there I would unplug that hole. It will help speed up warm up. I personally like a thermostat it keeps the engine in it's running temperature. If you decide not to unplug that hole then I would recommend gutting a thermostat out to give it just a little resistance but warm up time might be slightly longer. Just my thoughts and experience. Hope it helps.

 

Thanks so much for the explanation! I'll see if I can get the plug out of there asap, and get a proper gasket while I'm at it for the thermostat housing.

I really appreciate the explanation!

Cheers,

Paul.