so ive been having this overheating problem recently so i ordered a new water pump but it hasnt got here yet. today i got bored and took out the water pump and housing but i cant see any damage. the impeller looks perfect, the bearing seems fine......could it still be the culprit of my overheating? im going replace it regardless of whether thats it or not but....if it isnt....i dont know what else it could be.....the radiator could be partially clogged but when i flushed it recently it flowed pretty good so if there is any blockage, there isnt enough to cause such severe overheating. the water temp sender is new as well as the thermostat. also the fan seems to be working fine. i havent noticed any significant leaking anywhere. ill replace the water pump when it gets here and flush the radiator again and see if that works but......if it doesnt......what could it be? could a oil cooling problem cause this much overheating? i mean i drove it for less than 10 minutes and the gauge came close to maxing out. could a bad OMP cause this? what about the oil cooler? my model is in the sig. i really need to get this fixed, any help is appreciated.

 

Should tell us when and how long you have had this overheating problem.

Explain this statement "havent noticed any significant leaking anywhere"

You shouldn't be leaking any amount of water otherwise you won't get the system to pressure at 13lbs or so, By having a pressuried cooling system it will raise the boil point of your coolant.
The only times I every had to change a water pump was when it was leaking from the front seal thru the small weep hole built in the waterpump.

You said you replaced the themostat, it is factory unit with the jiggle pin at 12 o'clock position.

Flushing the radiator??? It still could have plugged tubes, are you running distilled water? Is the radiator is fairly old you should look for new unit.

Stock clutch fan is really only for speeds under 45mph or so,

 

im not positive how long ive had the problem but it hasnt been for TOO long...maybe the past 3-4 weeks at most.

i checked for leakage behind the water pump pulley but there wasnt any and i havent been losing any coolant.

i bought the tstat at autozone. i started noticing overheating before that tho. it seems to progress more than happen suddenly. before i noticed anything wrong the water temp gauge stayed around 1/3....then it started to stablize around half way but sometimes it would go higher. this is when i replaced the water temp sender and t stat. then it started to get worse. i just put on my new dual belt alternator pulley and when i took it for a test drive, this is when the water temp guage got REALLY high.

so after i install the water pump then i guess ill start saving for a new radiator.

 

dude,
do yourself a favor and get a Mazda thermostat. also, it may be worth your while changing the radiator cap as well.

does your car start running hotter in local driving or highway or both?

 

another possable culprit could be an electrical earth problem, i had a similar prob, so i put some temp plate recorders on my radiator, and they showed No increase in temperature above normal. what it turned out to be was a bad earth. Make sure the engine is actually overheating first..


these are the Stick on temp plate recorders i use. a nice reliable backup if my temp guage fails in any way.
The dots will go black when the temp is reached. i have only ever seen the 180Deg go black on ym 7, but when my 4x4 split a heater hose, the plate showed the temp reached 230deg

(oh, i dont know where to get them from, they are designed for use on Aircraft! stole em from work)

 

both

im gonna order the tstat from VBritish next and then maybe get a new cap

ultralights, ill do some research and see if i can find them...does it make a difference where you put them? well i guess if i put them on top it shouldnt go over 180 cause thats when the tstat is supposed to open

 

Your symptoms sound like t-stat, water pump or radiator. My bet is tstat if its missing the bypass block, or then radiator, wp 3rd.

Hah ultralights, I got a few of those too!

 

GET ONLY A MAZDA T-STAT Worth the 18 Bucks.

 

whats the difference between the mazda one and VB?

 

Alot of the aftermarket ones dont have the block off for the bypass hole, which allows coolant to recirculate instead of going thru the radiator.

 

well on the one i have now from autozone on the bottom of the tstat there is a metal plate held down by a spring that covers the bypass hole...is this what your talking about?

 

also, when a radiator gets clogged, what does it get clogged with?

 

Yes, I run autozone tstats too, on my racer and streetcar. Your ok if you have that style. Mineral deposits from not using distilled water usually, also crud from old antifreeze if its been in too long.

I'll tell you straight up, I replaced both radiators in my 7's with autozone replacements and the temps dropped alot. From 1/2-5/8 down to 1/3 on the gauge.

 

Also, check your cooling fan to make sure your have the required torque.

 

well i put the new water pump in and i flushed the radiator the best i could....i just have to get all the hoses back on and fill it up and see if it made any difference. i was using premixed 50 50 but i dont know what was in it before i got the car. i dont think it was the water pump cause i examined the old one and nothing seemed wrong, but its new now so i wont have to worry about it going out for a while. so ill see if flushing the radiator again helped at all. something still seems not right tho, if the radiator is partially clogged it would run warmer but when i drove it the gauge almost maxed out and if i wouldve kept driving it wouldve just kept getting hotter and hotter. doesnt seem to me that a partially clogged rad would cause this. is it possible for the coolant passages to clog? maybe the seals are bad somewhere and oil got in and left deposits....is that possible? or back to the electrical...how frequently does the guage itself go retarded? the temp sender is new. i would think that when a guage goes out the little coil would burn out and it wouldnt work at all but it does work it just reads really high. this is getting really frustrating

 

Sorry your getting frustrated. I know it can be a PITA. The shop manual shows a test of the gauge/sender, but youll need resistors to simulate the sender readings.

 

the haynes manual doesnt say how to test the guage, just how to take it out...lol

resistors arent a problem i know all about that stuff

do you know of a link that tells me how to test the guage

i want to test the guage before i move any further into the radiator thing so i know for sure that it is overheating or not

what about the coolant passages getting clogged...has it happened before?

 

Yes, but the temp is measured b4 that ,clogged passages wont show that way.

Ok here you go.
full cold (first mark) 233 ohms. next mark 104.1, middle has nothing, 3/4 next mark (about) 21.1, H mark 16.1

 

are those values universal for all FB guages? mines just has the 2 marks, C and H.

if the passages are clogged its stops the water from circulating through the engine and getting cooled at the rad so its just sitting there and gets hotter as teh engine gets hotter

BTW thanks for all the help, i really appreciate it

 

It's telling you to come buy my SE, that doesnt' overheat.

 

...actually i probably would if i had any money, lol

 

Damn, That should be for 84-85 cars. I dunno about earlier models since they have a different gauge.

Yea I guess you could see it that way. But remember, those passages in the engine are much bigger than the ones in the radiator. And about the post on checking the fan, the fan is un necessary above about 30mph. If your getting too warm even when moving, then it aint the fan.

No problem, happy to help.

 

You didn't use any silicone RTV to seal the thermostat, did you? I had a BMW that was overheating because the previous owner used RTV to seal the t-stat, and when the t-stat cover was bolted back on, RTV squished out into the t-stat obscuring the opening. Took it out and cleaned out all the RTV and it worked fine.
Just a thought.

 

no i used regular gasket sealer. maybe i just got a bad tstat, i will see what happens when the VB one comes in. then i will test the guage. hopefully one of those is the problem. if it isnt then i guess ill have to get a new rad. if it comes to that and it still doesnt fix the problem i think im gonna go insane