Hi I'm new to this club but have read a few of the previous messages etc. I have a 1200 coupe which I use for rallycrossing and gravelsprinting etc. My problem is that it overheats. After
about 6 laps at taupo circuit the temp gauge is right off the clock (new aftermarket guage) and it just won't cool down. I have a radiator out of a Toyota Hiace van (two-row cross-flow
radiator)which is about twice as big as a standard radiator. I have a 12" electric fan which doesn't make any difference either. I have had the radiator cleaned out as I thought it may have
been blocked but the radiator repair guy said it was hardly blocked, he reckons the radiator simply isn't big enough for the motor, but it is only a mild A15. I wouldn't fit a much bigger
one in the car anyway, unless I went to a 3-row or more. I have tested the thermostat and it's O.K. I run 50/50 glycol/water. Does anyone have any ideas?

Cheers,
Morgan

Have you checked your water flow? Could be a waterjacket/pump problem. I had this happen once to a friend's Mitsi - the pump impeller blades had dissolved so there wasn't
what you would call brilliant water circulation. It was overheating pretty chronic - but then it was a Mitsi!! Have you got Matthew's old coupe or is this one you've built
up?

It might just be your gauge. Where does your gauge sensor sit on the head? Hopfully it is close to your thermostat so you can get the same reading. How does it compare to the factory thermo
gauge?
Take the thermostat out and put it in boiling water on the stove and use a reliable meat thermometer (not one that has the different meats on it but one that actually has numbers on it).
Watch the thermostat and check the degrees when it opens up. Put it back it and run the engine with the top off the radiator and with the same thermometer in. Watch for the flow in the top
of the radiator (your thermostat has open. Check the degrees again and it should be the same then check your gauge in the car and note any differences. Let it run and see if the temp rises.

If it does, you need a bigger radiator.

I have a Stewart Warner gauge that reads about 10 degrees higher.
At least you have a place to start.

Ernie

Hey Morgan,
Do you have the same overheating problem when running on straight water? Glycol is an anti freeze it actually increases the temp of the water, to beat the cold. I don't run anti freeze in
any of my cars but I do add add an anti corrosive product. Another thing what is your timing like, can you run it on the road does it get hot just idling? It should'nt be too hard to
solve.

hey Morgan, is that you man? its me chris, i got the coupe, my dad owns MotorDrome and i work across at David Jones, is the car still in taupo? bring it over to me and i will have
a look sweet as, and i got those prices for those tyres for you, but i cant say the prices here as they are a special price.
sweet! yeah man.
choice from chris.

You're probably on to something Chris - do ya reckon he needs his rocker
cover tweaked?

When all else fails to keep a motor cool under heavy use, go to a cooler
range spark plug.

Hi, me here again.
Thanks for all the replies! I initially thought the guage might be reading high too. The sender is in the original factory position. I think it is reading O.K. though because it got so hot
it nearly seized and blew the head gasket. It is still running alright so I don't think I did too much damage. I'll probably pull it down and freshen it for next season anyway. I have tested
the thermostat in a pot of water on the stove and it's O.K.- should be too, it is almost brand new. I haven't taken the pump off but it should be sweet as it was brand new too, the motor has
only done one season, probably not much more than an hour or two running in total. I built the car from scratch. What would the timing do? Could that make it overheat? We reset it to where
it was originally when we built the motor, I've been meaning to advance it to get the most out of it with Avgas but didn't get round to it. It does overheat idling now but I think that is
just because the head gasket has blown. Yeah Chris it is me the car is still in Taupo. I'm pretty flat out at tech at the moment with exams and stuff so I won't be able to get it down to the
bay for a while. I'm at work this weekend though, if you're calling past call in.

Cheers for the help guys,
Morgan.
PS- I tried tweaking the rocker cover, but it didn't seem to make a difference. Did I tweak it the wrong way maybe?

Dear Stirlingmac, I enjoy your comments & Ideas, you obviously have a lot of 'car' experience, I usually agree with most of what you have to say, but I have to draw the line at your comments
about glycol based antifreeze. Working as a machanic here in Canada you might say that I generally know a fair bit about antifreeze. The name of it confuses a lot of people. Yes its first &
foremost intention is to stop the rad. fluid from freezing. (We mix it up to 60/40, glycol/water for winter use, it sometimes hits -40 C here.) On the other hand we sometimes have
+35 C in the summer time. If you use a good namebrand antifreeze mixed 50/50 it actually raises the boiling point of you cooling system allowing it to run cooler. A properly mixed solution
also sticks to the internal parts of your cooling system to allow better heat transfer(both from engine parts to the coolant, & from the coolant to the radiater. Strait water doesn't cool your
engine as well.
I agree with your comments about synthetic oil, nothing beats regular oil changes for engine protection. For street use regular oil is a cost effective way to go. On the racecar that I used to
pit crew for, synthetic oil won us a regional championship. One hot race weekend we were leading our class during a roadrace when the oil temp started to climb. (the oil cooler was plugged
with debris from the track). It was either pit & lose valuable points or continue & hope for the best. The driver soldiered on as the oil temp continued to climb. The car finished without any
problems & the oil temp was far higher than regular engine oil could have handled. We collected max points that allowed us to win the season points title. So for heavy use or turbo cars maybe
synthetic might be what you'd want to use.(I prefer Mobil One synthetic, but like underwear we all have our own preference).

yeah i was meaning to say similar stuff man!
just for the record glycol doesnt raise the water temperature to prevent it from freezing, it mearly has a lower freezing point than H2O(flash eh) which enables it to resist freezing down
to -0 temperatures, which is a good thing, and at the other end of the scale it resists boiling which when combined with your pressure cap can give boiling points well in excess of 112
degrees C, just what i need on a hot day! it is also a fact that the glycol/water mixture conducts heat from metal parts more effectivly than straight water.
it is also green. i saw some blue antifreeze the other day, and red is also common. on my pre-apprentiship course a mango drink was mistaken for coolent and tested for its ph level.
anti freeze also tastes bad, and it gums up your oil if you blow a head gasket.
on race engines it is not really wise to use glycol based coolent for this reason, if the head gasket blows(and vents into the engine) with straight de-minerialised water and a sutibal anti
corrisive/water pump lubricant it is un likely to gum up the oil and cause a seizure mid race, as it can be a long way to the pits sometimes, where as antifreeze and oil mix and at the very
least can demand a compleate strip down to wash out the stuff.
yeah thats just my 5 cents worth.
oh yeah, and i belive that it was marieospeedwagon that wasnt to keen on the synthetics bro (bloxhamd), so yeah, as far as i know stirlingmac uses synthetics, yeah, sweet as man.
hey stirling mac (or any one that wants to answer) would a 10w/30 oil be too thin? as castrol has that new protec 10w/30, its just that im not 100% keen on the turbo tested 15w/40 as i have
heard about consumption problems with that oil, and as dad gets the 10w/30 in bulk (read bulk!) it works out quite a lot cheaper than GTX3 10w/40, yeah, choice guys, drive hard and all
that.
my fuel hose has scarred my fire orange rocker cover paint job :( but it still goes just as fast! sweet!
choice from chris.