MZ20 (7M-GTE) heat issues again...

[doobs]

Ey all,

The Soarer seems to be having some heat problems again. I thought I was on top of it but with this hot weather it seems I’m not, here’s the story...

(Sorry its a little long winded, but I want to give everyone the full story... Also when I say +1or +2 its in reference to the middle of the temp gauge)

Down in Geelong we have had some very hot days, while today was not the hottest, it was very humid and sat at about 24C.

I started the car off cold, and took it for a 15min drive around the roads out the back of my house, they are very quiet, I took it easy, and the temp settled in the middle.

Then I began to put the foot down, pushing the car as hard as I could go, with in 5 - 10 mins the temp started to alternate between middle and +1, I was a little concerned but I kept going hard, I took on some gravel roads, within 5 mins or so the car was then alternating between middle, +1 and +2.

I know this is not normal, so I backed off, took it easy, and the car began to alternate between middle and +1 again, I got home and let it sit there, after 20 seconds of idling the temp moved from the middle to +1 then 10secs later it moved to +2 where it sat for 10secs until I decided to turn it off...

When I turned it back on it was at +3, then went to +2, then +1, I held the revs at 2000 and it went to the middle, I let it back to idle and it went back to +2, so I turned it off again.
I could hear a lot of bubbling when the car was off, which was coming from the overflow tank, I guess the car was letting out the pressurized water...

Generally I only drive the car for 30 mins at any one time, and it usually sits at the middle for the whole drive, longer drives it might go to +1 for 10secs then go down again, its only when I give it some it seems to get to +2... Stop start driving after a 20 min warm up drive also seems to get it up to +1 and +2

I have compression tested the car, and all cylinders are 160, both the oil and water are free from each other, I had the system pressure tested and the radiator place said it was fine. I’ve had both the water channels in the engine and the radiator cleaned, and I’m using tectaloy gold coolant. The radiator place said the thermostat looked fine… but who knows, they also said the car was fine…

I guess it narrows my problem down to one of/all of, 3 things: water pump, thermostat, or radiator cap (I have tried 2 caps both rated at 0.9)

What would you try replacing first?, Is there any other tests I can do? or should I just replace them all?

Thanx fellas

[RyleyMA61]

unsure of your next step mate, but i had pretty similar symptoms when my 7m had a minor BHG... sorry to say it! temp gauge went up minorly with normal driving and idling, i'd rev it a bit and it would go down... but be fine when it was cold etc....

mine was bubbling in the overflow too. ive heard some bubbling is normal, but since having my HG fixed it hasn't bubbled.

hopefully it is just a rad cap/thermostat!

good luck mate
ryley

[doobs]

Yeah I'm totally cool with replacing the head gasket if need be, I just want to be sure what the problem is first...

[ndgcpr]

is it running the motor fan or a thermo one?

I guess if the radiator is getting hot then your water pump works fine

[doobs]

The car has both a motor fan and a thermofan, + 2 mini fans which I beleive is for the air con.

[Yian]

D'oh... another 7mgte bites the dust *sigh*

The temperature should not fluctuate at all, thats all I can tell you. I drive to see my missus in the mid 40s for an hour being in traffic, with minor spurts off the traffic lights, and not once did the temperature move above midline. It did drop below midline once or twice, but I attribute that to the clutch fan engaging and pulling much more air through.

http://www.toymods.net/forums/showthread.php?t=2041

Some discussion of MA70 heat problems.

Yian

[ndgcpr]

dam thats alot of fans, but like Yian said, it really shouldn't move from the middle

[BlackSupra]

Mine sits 1 bar below the middle all the time.

Another sick 7m.

[Cressida91GLX]

I will really hate to say it is a sign of BHG and a tee-kay test from a radiator shop can confirm. Compression test is not the best test for BHG. It might be a minor BHG as you don't have rough idle and other issues associated with the 7m BHG.

G/l with it and don't spend money on things which are not wrong, get it fully tested for BHG first.

[doobs]

Hmmm, seems like the best thing for me to do is get a TK test done... can some one explan this test to me so I dont look like a total dick when I get it done?

Cheers

[EldarO]

just take it to a place like natrad, auto bahn or somehting along those lines, and tell them you want a TK test done, i did this yesterday, and next week auto bahn is stripping down my 7M to replace the r00ted gasket.

mine was blown between the water galleries and cylinder.

i had no other signs of BHG, just overheating.

Sorry to say dude, but get the test done and find out for yourself

Eldar.O.

[doobs]

Thanx for the replys, BHG was gonna happen sooner or later.. but time will tell...

[whatthe?]

Tee Kay test is teh shiznitz. Dont spend anymore money til you get it done.

[doobs]

Dam sunday, no one is open, so it will have to wait until after work tomorrow...

[EldarO]

I know EXACTLY how you feel, Whatthe? told me about the TK test last wednesday, the day after was Australia Day, so i was anxious to get it done... and i had to wait for friday morning

It was like waiting for that really important exam result :/

Eldar.O.