Drilling the thermostat??

[undy]

I actually have 2 or 3 infrared guns laying around.. I'm a HVAC contractor and have quite a bit of knowledge of heat rejection etc.. I use them on the Cobra all the time (checking individual header primary temps helps with adjusting 4 corner Holleys and Barry Grant carbs)

The temp gauge appears to be operating correctly all the rest of the time so I suspect it's working correctly when it's reading 250 deg. There's no potential difference from the sending unit's housing to ground too (good ground contact). It's conceivable that there's a 250 deg pocket of steam flowing past the sending unit while the rest of the system's not up to temp. That would account for the disparity between the gauge reading and the "feel" of the intake. I'm thinking (hoping) that the 4ea 1/4" holes will take care of the steam pockets. If they don't then I need to rethink my problem solving tree and look elsewhere for the problem/solution.. I'm banking that's not the case. The head gaskets are fine (I assembled). If they weren't I'd be overheating all the time. The gauges are electric, not cap tube. All the Robertshaw (Milodon and Mr. Gasket) high flow thermostats (BB Chrysler and the smaller current style) have the same diameter openings, so there's no advantage there as I'm using the Robertshaw now. I'm running Water wetter too. You need to stay away from tap water (I used distilled water) as it contains too many conductive minerals which promote galvanic corrosion and electrolitic activity.

Coolant recovery kit??

Thanks for the help/suggestions,
Dave

[undy]

last post didn't show up??

[RICK LAKE]

Undy He have a coolant flush and fluid transfer machine that removes the coolant after run to operating temps. Vacuums the whole system down and replaces with new coolant. The vacuum parts keeps air pockets and air from being caught inpockets in the heads. Have you tryed to purge the coolant system with the motor on the first startup cycle? The best place would to be at the highest point of the coolant system on the motor. I would try cracking the sensor and see if coolant leaks out or air. If air, you may have to do this 4-5 times to purge the system. LS1 motor have this problem. It's possible to have 1 head gasket in wrong on the FE and run the motor for over 1 hour and just start to overheat. I know I mounted one wrong. Motor ran fine. but over an hour the temp was at 220 with a 180 thermostat. Plenty of flow of coolant but running hot. Try the holes, IMO I think you are going to push too much coolant through the thermostat housing without letting it heatup. It may fix the spike problem but might hurt the effectiveness of the coolant system. Dave I will get you the right number of STAT tomorrow for the thermostat with the larger opening. You must have alot of air in that motor that after 5-10 drives and till having this problem. I wonder if you have a head gasket not sealing, and it is bleeding compression gas into the coolant system. Motor heats up and the expansion is stopping the leak. Motor cools off and you have the air in the system again. What combo are you running, iron block aluminium heads, iron heads aluminium intake, all aluminium?? You have a recovery bottle so the hot coolant goes in there and when the motor cools off it is sucking coolant back into the motor but not all. There is a tester kit for checking combustion gases in the coolant system. Rick L. Ps used to drive on VA beach in the 70's, there was a patrol guy on the beach in the summer with a black jeep still there? I lost $50.00 to him in a drag race on the beach at 2:00a.m. Still a great beach for the sites.

[afret]

I don't run the bypass. I drilled three 3/16 holes in the thermostat. It does take a bit longer to warm up. I copied what Stewart does with their thermostats where no bypass is used.

Stewart Components - High Performance Automotive Cooling

[undy]

Rick,

I'm running the Pond 482, all aluminum. It's not and air entrapment problem as all other times, other than the intial temp spike, the temps are dead nutz on (between 180 to 185). I can, even after a long (hard) drive, let the car sit and idle in 80deg weather and the thermostat will modulate open and closed to maintain 180 deg. I let it set running like that for 30 minutes w/no increase in temps. Air inthe system is not aproblem. I did the "wrong side up" on the head gaskets on a 428 I built so I know the head gasket dilema, not an issue here. I'm about as sure as I can be that it's just too low flow through the engine w/the t-stat closed, stem pockets and the whole mess. Afret, I bought another t-stat, talked to Stewart Componants Technical, and have drilled 4ea 1/4" holes. I'll install today and report back on the findings.

btw, fyi.. I've a AAS in Automotive Technology and a "not-current" master ASE cert.. so... pretty heavy w/theory etc. knowledge.. It's Just a hobby though .. as HVAC pays much better here.

Yea, Va beach is the shiznits during the summer. The co-ed Russian babes are here all over the place, dressed in minimal garb. ...and eager to dive head-long into Capitalism

[Jim Dewar]

UNDY, How did your 4 holes turn out?

[undy]

I did the 4ea 1/4" holes and they worked fine ... well ... they worked too good. I drove it a couple times in 50+ deg weather and I had problems building enough engine coolant temp. I was wondering if that was going to be an issue. I bought another thermostat (my 5th Mr. Gasket stat I bought and modified, I'll get it right yet ) and I'm going to do the 3ea 3/16" holes on this one, per Stewart Componant's recommendation and post results.

The short answer though is yes, it did eliminate the high temp spikes prior to the thermostat opening.

Dave