So this afternoon got the rear quarter windows tinted and was feeling my oats, and stupid me forgot to shift soon enough and just touched the rev limiter for a second.

!0 minutes later I see steam out the back and see the temp. light is on. Pull over, shut the engine off, open the hood and I can see where coolant had come out from under relief on the cap from the aluminum coolant tank.
Fans are on. Coolant all over but no obvious leaks and the hoses appear to have pressure.
Wait a few, start it, no steam or stink from the exhaust, and no bubbles in the coolant tank so I think that rules out a head gasket.

I let it cool and limp home, [a few miles] with the heat on which is blowing hot. Maybe 2 miles light comes on again so I stop and let it cool. Still no obvious leak.

Get back to the house, fans are on. I let it cool, start it and add coolant. Weird noises from the coolant tank which go away after less than a minute. Screw the lid back on and let it idle which it does for at least 10 minutes, [no light but the heat was on] Turn the heat off, and a short time later, [3-5 minutes] the fans come on a few minutes after that, the light's back on.

I let it cool, check the level, then drive about 10 miles to my shop and no light. [heat on, turning the engine off at lights, turning the engine off and coasting down hills.

Get it in the shop and the fan is on right away but nothing out of the pressure relief on the cap. Looking all over and don't see an obvious leak.

The engine is hot but not boiling hot, but the front hoses aren't as hot. Engine running, open the bleeder screw and some, [more than a little but not a lot] air comes out. I was hoping that was something but then realized the coolant coming out of the front bleeder was cool and the hose was pretty cool.

But no obvious leaks. But right about then I walk to the drivers side and see a fair amount of coolant running from under the car.
I was just about happy as I thought I would find a bad hose or something. Put the car up on jack stands, crawled under and from what I see, nothing obvious.

My buddy just brought a pressure tester over so well see what that does.

I would think with the heater working it would indicate the water pump is functioning. One of my thoughts, [with the cool hose] was with hitting the rev limiter I could have share the connection between the supercharger and the water pump.

Any ideas???

rob

 

Update.
Pressure tested, held 20 PSI with out dropping at all for more than 10 minutes.

When rebuild took place, new water pump and new thermostat . Since build I've put about 400 miles on it without issue. {maybe hit the rev. limiter 1-2 times with my initial exuberance]

I keep going back to hitting the rev limiter [today, as it overheated 10 minutes later] and damaging the supercharger to water pump connection, But if the pump wasn't circulating I wouldn't think I would get heat from the heater core, [from lack of circulation]

I refilled the system [with water at this point] and bled it from both screws. I guess I'l try running it again.

Any ideas?

rob

p.s. If anyone is interested, the same fitting for the brake system pressure bleeder fits the aluminum coolant tank.

 

Some additional diagnostics;

After filling everything up and bleeding the upper hose and the bleeder at the T-state housing, let it run for 10-15 minutes.
The coolant tank became hot. [can't keep your hand on it hot]

The upper rad. hose was not hot.
The lower rad. hose was pretty hot.
Top of rad not hot, [the only spot I could get my hand on]

The fan came on after a few minutes.
The Lower hose was not "quite" [at least not as hot as the tank] as hot, the upper hose was almost cool.
Upper hose bleeder was almost cool. Coolant from the upper bleeder is barley warm.

Turned the cabin heater on, after a moment the rad. fan went off.

Turned the heater off and after a few moments,
Coolant tank measured 180 degrees.
Upper rad. hose at bleeder; 89 degrees
Lower hose, 160 degrees.

What this tells me;
1. no external leaks, [pressure held]
2. coolant is not circulating [temp difference between upper and lower hose. [new rad. but it really takes a lot to clog a rad.] I think?
3. Is there any way any of this could be tried to the over -rev? [seems like an awful big coincidence]
4. 2 weeks, 400 miles and all of a sudden the T-stat takes a dump? Seems unlikely, but not impossible?
5. Supercharger to [new] water pump connection? Anyone have any experience with this? I mean it's metal to metal.
6. Easiest thing first. New T-stat tomorrow.

Again, any hints? Am I missing some weird Mini thing?

Rob

 

Sure you did't put the thermostat in backwards?

 

JAB,

I don't think so. If you look at the thermostat and gasket close it really wants to go together only one way and I was pretty careful with making sure it was right. Plus I put 400 miles on it running it around pretty good so I would think that would have shown up before now.

I looks like the coolant is def. not circulating. I had put in a new radiator, new water pump and a new thermostat and an aluminum t-stat housing. I started taking things apart last night to get to the thermostat housing, as that's a lot easier than getting to the water pump.

Has anyone ever heard of a brief over rev damaging a water pump? Just seems awfully coincidental that it overheated 5-10 minutes later.

rob

 

I took the thermostat out and it was installed correctly.

On close examination the top of the post was missing and there was just what looked like a piece of nylon remaining, so I have to assume the entire post was nylon.
The new thermostat has what looks like a brass shaft.
When heated up the new thermostat opened correctly. The old one did nothing and eventually. spit the little piece of nylon out.

My advise is to reject any thermostat that has a nylon shaft.

And don't forget the cap on the "Powerbleeder" , brake system pressure bleeder, fits the aluminum coolant tank and can be used to pressure test your cooling system. I can't say if it fits the OEM plastic tank as it's at my shop at home but I'll check.

Rob.





Right under the wire tie is the small nylon piece that remains of the shaft. It should go all the way to the top above the wire tie.





New thermostat on the left. Plastic part POS on the right. Just say "No" to plastic...