Cool Runnings

[mingo]

MGB Roadster 3.1L Megasqirt EFI. My issue is it runs too cool. 50* outside temp running back roads at 70mph. Temp gauge never gets above 140*. The ECM never gets out of open loop b/c temp is set at 160*+. Sitting at a traffic light or just letting it idle it will climb to 200 and my fan will kick in. As soon as I get up to speed on the road it will go back down to the 140 or below. Is my thermostat bypassing? I've seen other threads about this, with no outcome posted.. I watch the tables while hooked up to the ECM. I never goes to closed loop while driving. Only when sitting still. My AFR are 13-14 while driving. Alittle too rich.....

[carbon]

The only way this could happen is your thermostat opens at 140*... or you don't have one. I would try a new thermostat...

[neophile_17]

Some thermostats are made to lock open if you go above a certain usually very high temperature. This is to crutch a cooling system failure. If this is the case you may be able to pull it out and reset it or buy another thermostat. I'm assuming you verified that the sensor is correct.

Good luck!

[GM Ontairo]

Mingo my apologies for not updating my thread - http://60degreev6.com/forum/showthre...rently-stumped

I was trying to sort out the issue and my ignition control module failed and I was on a short vacation back home at the time. The truck has sat parked (5000kms away) ever since and this is still not resolved for me either.

Just to clarify. I installed a griffin aluminum rad rated for 400hp and dual e-fans. I also converted from the old v-belt drive to a serp set-up with the newer timing cover & water pump. Ever since this the truck will not come up to temp when driving. Same situation, if it sits and there is no air cooling the rad it will slowly come up to 195f and then my fans kick on and drop it back down immediately. As soon as I hit the road it will never come above 160f. Temps were all verified with an infrared thermometer.




Nothing changed. The truck would come up to temp and then go further until the e-fans came on. As soon as I started driving it, it would drop right back down to 160f. I shot the thermostat housing and just below the intake with an infrared thermometer to ensure my gauge was working properly. All temps were verified with the infrared thermometer.

I thought maybe coolant was just simply bypassing the thermostat around the sides because there seemed to be a little bit of play in the intake recess for it.

So I made up this little rubber gasket just to ensure this wasn't the problem.







Nothing changed. 160f cruising temp all day.
I then pressure tested the rad and changed out the rad cap. No leaks, pressure held at 15 psi for 20 mins. Rad cap is functioning properly.

I now decided to throw in a jet 180f thermostat to see if anything changed. No change, 160f cruising temp.


Mingo is your cooling system stock?

So I then started researching motorad thermostats and found a lot of bad reviews about how the springs are weak and they prematurely open and run motors cold. So I went out and bought a stant 195F the next day. I was so sure this was the problem. Nothing changed 160f cruising temp.

I also pinched off the heater core lines to make sure nothing foul was happening there, no change. Then tried flipping the thermostat for curiosities sake. No change either.


Is it possible the thermostat is cracking a touch or the air bleed is letting enough coolant through to drop the operating temp?


also to answer 45es's question revving the motor while sitting still does not drop the operating temp. It just increases it quicker while at a stop. As soon as I start driving it drops back down to 160.

Would love to hear what you guys have to say.

[mingo]

Mingo my apologies for not updating my thread - http://60degreev6.com/forum/showthre...rently-stumped

I was trying to sort out the issue and my ignition control module failed and I was on a short vacation back home at the time. The truck has sat parked (5000kms away) ever since and this is still not resolved for me either.

Just to clarify. I installed a griffin aluminum rad rated for 400hp and dual e-fans. I also converted from the old v-belt drive to a serp set-up with the newer timing cover & water pump. Ever since this the truck will not come up to temp when driving. Same situation, if it sits and there is no air cooling the rad it will slowly come up to 195f and then my fans kick on and drop it back down immediately. As soon as I hit the road it will never come above 160f. Temps were all verified with an infrared thermometer.




Nothing changed. The truck would come up to temp and then go further until the e-fans came on. As soon as I started driving it, it would drop right back down to 160f. I shot the thermostat housing and just below the intake with an infrared thermometer to ensure my gauge was working properly. All temps were verified with the infrared thermometer.

I thought maybe coolant was just simply bypassing the thermostat around the sides because there seemed to be a little bit of play in the intake recess for it.

So I made up this little rubber gasket just to ensure this wasn't the problem.







Nothing changed. 160f cruising temp all day.
I then pressure tested the rad and changed out the rad cap. No leaks, pressure held at 15 psi for 20 mins. Rad cap is functioning properly.

I now decided to throw in a jet 180f thermostat to see if anything changed. No change, 160f cruising temp.


Mingo is your cooling system stock?

So I then started researching motorad thermostats and found a lot of bad reviews about how the springs are weak and they prematurely open and run motors cold. So I went out and bought a stant 195F the next day. I was so sure this was the problem. Nothing changed 160f cruising temp.

I also pinched off the heater core lines to make sure nothing foul was happening there, no change. Then tried flipping the thermostat for curiosities sake. No change either.


Is it possible the thermostat is cracking a touch or the air bleed is letting enough coolant through to drop the operating temp?


also to answer 45es's question revving the motor while sitting still does not drop the operating temp. It just increases it quicker while at a stop. As soon as I start driving it drops back down to 160.

Would love to hear what you guys have to say.

My system is far from stock. A aluminum radiator for a 69 mustang.( fits in the MG) and a 17" span fan for cooling.

[GM Ontairo]

My system is far from stock. A aluminum radiator for a 69 mustang.( fits in the MG) and a 17" span fan for cooling.

Any success with your problem mingo? I'm going back east in a few weeks to work on the truck and would love to get this solved.

[mingo]

Bought a new thermostat. Compared the two The spring in the current one was extremely weak. Took nothing to get it to open. The new one had some resistance to it. I installed the new one and it's now runs a consistence 200 degrees. My AFRs now are in the 15 a 16 when cruising down the highway. Goes into closed loop. Must have been a weak spring letting the coolest bypass to much.