408 getting hot

[FST FOX]

I only have maybe 200 miles on this motor, initially went with a 180 T-stat and got about 220 on these cool Tx days, well put in a 160 T-stat and now I am pissing everywhere on normal short drives, I have fans working properly and everything seems normal, T-stats are opening just keeps getting hot, I am going to do what James Yale suggested and put the front on ramps and then let it run since the deck height is higher and is almost even with the overflow tank. If not I might have to upgrade radiators and switch to a better single fan over my 2 small ones, anything I am missing, or is this just normal growing pains with a fresh tight motor?

[Keithc8]

This is not normal and there must be a problem somewhere in the cooling system. Make sure you do not have air trapped in the system. When you fill up the over flow tank you need to run till thermostat opens and then top of. We pull a vacuum on the cooling system to make sure that we get all of the air out. Make sure that your belt is not slipping and that your fans are pulling the air the right way. Good luck, Keith

[FST FOX]

Should I run the 180 or 160? also I am going to take advise from a BDR dealer and run it with the nose up to ensure all air is out of the system, other than that I might be forced to upgrade radiator and fans in the future. Thanks for the quick response

[bobcowan]

Back the timing off a couple of degrees. Check your fuel mixture. Have the collant tested for products of combustion.

[Bluesman]

As mentioned by Keithc8, air could still be in the cooant trane. Burp it out. New motor. What is becoming popular is the electric water pump. Once the calculated gpm is known, a water pump that provides the same flow at all times can help.
It is no fun to constantly be looking at a temp. gauge. 220 is a bummer.
Good luck.

[CowtownCobra]

I see 220 in stop and go on a warm/hot day. Otherwise it likes to run 200 at moderate speeds and 180 on the highway. With a 16 lb cap your coolant shouldn't boil until around 240.

[CHANMADD]

It seems that a lot of folks have problems understanding the cooling system!!
The reason that a thermostat is installed is so that the engine can be kept at the best (most efficient for combustion) temp, without boiling over. 190 degrees to 200 degrees seems to be a nice temp to run at and is maintainable without to much hardware.
The thermostats job is to keep the coolant in the engine block ,and heads, until it is at max operating temp.Then the thermostat opens lets enough hot coolant out and into the radiator where it can be cooled. At the same time from the bottom of the radiator (Cold side) cool coolant is allowed into the engine to....Cool it down.
If the thermostat opens too soon, IE a lower temp, Then because the coolant is most always above that temp , the thermostat remains open all the time,so that the net effect is the same as having no thermostat. The coolant is flowwing as fast as the water pump is pumping. The coolant then does not stay in the radiator long enough to be cooled and returns to the engine still hot.
So if you want your engine to run at 190-200 put a 190 thermostsat in and keep a low pressure radiator cap.I like to run no more than a 13 pound cap ,less pressure to blow out seals and gaskets and hoses etc!!
John

[madmaxx]

Never run any engine without a thermostat. The reason being the velocity of water through the engine is to fast thereby creating a larger than acceptable boundry layer next to the block. In simple terms there is not enough residence time for the water to take the heat away from the engine. Even a failed open thermostat acts as an orfice controlling fluid velocity through the engine.

[ameriperformanc]

Hi

if any of the solutions doesn't work, you might check if the head gaskets we're installed
properly, i've seen the wrong gaskets in a brand new package,even if you're engine was professionnally build, it can happen...........so , as a last resort, it might be worth it to check on them........

good luck

AL

[FST FOX]

I'm going to go buy a 180 or 190 and then burp the system again in the afternoon, the above mention about consistant flow makes alot of sence and now i realize (I hope) I found the mistake that is making this thing run hot

[fsstnotch]

make sure to drill about 1/8" hole in your t-stat to allow the air out.

Madmaxx, that is why they sell restrictors. In my mustang, i ran an fail safe that was no good. I never had cooling issues.

[FST FOX]

Originally Posted by fsstnotch

make sure to drill about 1/8" hole in your t-stat to allow the air out.

Madmaxx, that is why they sell restrictors. In my mustang, i ran an fail safe that was no good. I never had cooling issues.

So I should drill a hole no matter what?

[fsstnotch]

Yes, drilling the 1/8" hole allows any air trapped in your engine to escape

Quick explaination i found on the net

The Thermostat Bubble Connection
By Steve Litt
A.S.E. certified master truck and auto mechanic Dennis Buler emailed me, mentioning he's solved many overheats by drilling a 1/8" hole in the thermostat. Dennis explained that if any gas, be it air, combustion gas, or steam, gathers around the thermostat, that often the thermostat can't detect the coolant heat, and therefore doesn't open. If only the thermostat would open, the gas would be "blown" into the radiator. And of only the gas were "blown" into the radiator, the thermostat would open. Catch 22.
Dennis explains that his 1/8" hole provides an escape route for the gas without passing so much coolant that the engine runs too cool. In other words, the thermostat will simply open less in order to maintain temperature.

Reading Dennis's email, my mind drifted back to all the emailed symptoms where the car overheated in the first few minutes, then magically dropped back to normal temperature throughout the rest of the trip. Could it be that when cold, air surrounded the thermostat. The thermostat therefore didn't open at the proper temperature. However, when the engine temperature reached overheat levels, maybe the thermostat opened, blowing out the air. The opened thermostat would allow the cooling system to do its job, returning to normal temperature. The partially open thermostat would prevent a gas buildup. Until the car was shut off long enough that the thermostat would completely close :-)

Dennis's findings might suggest that running for an hour with no thermostat might be an excellent test. If overheating occurs with a known good thermostat but doesn't occur without a thermostat, it's a strong suggestion for Dennis's air bubble scenario.

I don't know enough yet to make drilling the hole a suggestion. I don't know its side effects and risks. But it sure sounds reasonable. Add that to the fact that Dennis says he's seen several foreign thermostats come from the factory with a 1/8" hole, and the fact that another Troubleshooters.Com visitor mentions in an email that VW Rabbit owners often drill such a hole to eliminate engine airlock.

If you want to try it (and once again, I don't know enough to recommend it), you can see the location of Dennis's proposed hole in the diagram below. Here's how Dennis describes the location verbally:

"i drill the hole in the flat disk part like half way between where the gasket would seal and the center opening mechanism" Pink dot represents the 1/8" hole

[CHANMADD]

Make sure the hole is at the top.

[madmaxx]

fsstnotch

Thanks!! and excellent idea, how comical i was working on my father in-law sailboat Kubuta diesel last weekend and could not get the cooling system to bleed until about an hour of trying. As you indicate I could not get the thermostat to open and the temp kept rising, it did have a peacock on top of the thermostat but as you said above if the tstat does not open what good is it.

I agree 1/8" hole is small enough to not affect flow but big enough to let gas out!!!

[fsstnotch]

I can't take credit for it! Someone on this site told me about doing this and it made total sense! I don't remember exactly who had said this, but it is a great idea!

[Jim Dewar]

Searce this Thread "Drilling The Thermostat". This thread solved my problem and sounds like a possible cure for yours

[jshel1]

Patrick,

Did you get things all sorted out when you switched thermostats ?
Any problems drilling your burp hole?