Hey guys -

Ran into a little problem last week. Engine started running hot (recently rebuilt, mildly worked 440, with huge Griffin aluminum radiator, really big fan and 160 deg hi-flow thermostat). The car had previously run fairly cool.

A closer look showed rust in the coolant, must have dislodged from the engine which had been sitting for "a while" before the last rebuild. Manually flushed the radiator and block. My mechanic said we might have to flush it again and suggested we run it without the thermostat for a while.

Drove it about 15 miles in normal street traffic (stop lights, 80 deg ambient temp) and the temp never got over 170.

So I know the drill about not running without a thermostat, but 160 - 160 is where it was with the thermostat So for the SUMMER months, any big deal about just not bothering to use one, providing it reaches operation temp fast enough?

(Yeah, I know, we always taught to ALWAYS use a thermostat ...)

Tks.

Archer

 

A lot of high built motors don't run thermostats. You should be ok, it'll just take longer to heat up. I would look into though. Maybe it was just a bad t-stat.

 

Tim -

Thanks, didn't know that. We literally took the old thermostat apart (with a saw) and it looked fine - I was kinda hoping it didn't.

Also, using a 16# radiator cap, is that the current thinking? Seems like there's rarely an over flow into the puke can.

Archer

 

You will need to find out what that car/motors is suppose to have on it stock and go with that. Each motor is going to be different. Then install a known good t-stat.

I had this problem with my j10 and turned out that the cap was the issue. I went with a 16 pound cap and it came stock with an 8 pound cap.

 

Tim -

That's part of the problem, there's very little stock on the engine/trans or radiator. I was going in the opposite direction, having too strong a relief valve on the cap wouldn't let the pressure bleed off quickly enough and increase the heat. Wondering if dropping down to a 12# (or lower) cap would help.

Archer

 

might be me, but 160 seems a little low. gets to be a buck-twenty here and i run at least a 190.

 

John -

Problem with the big blocks (at least mine) is that once I reach the 190 point, it's only a matter of time till it keeps climbing. keeping it in the 160 - 170 seems to work and gives me time to re-access when I get held up in traffic.

Such is life in suburbia.

And yes,there are redundant electrical and mechanical temp gauges and they are in sync.

Archer

 

I run a 160
you need a thermostat
without one, the car will actually run hotter
the thermostat privdes restriction for the water so it has time to cool in the radiator

 

Matt -

Sorta. The Thermostat, as the name implies, is a flow regulator. When the incoming water temp reaches a certain temp, it begins to open and allows water into the radiator to be cooled. The "required" temp is based on engine out put AND radiator cooling capacity. That's why some guys can use flow restrictors instead of stats.

In this case, I'm using a huge radiator and have a lot of air going through it. If I were using the stock one and and stock fan, you'd probably be right.

While 160 is on the low side, knowing how fast the engine can heat up, if this stays the way it's been, I may hold off of replacing the thermostat until winter, when the engine won't heat up as quickly. (Last winter, I had to use a sheet of cardboard to block off 1/2 the radiators surface.)

Right now, just trying to confirm what changed and seems like it was rust breaking loose. I wanted to see what folks takes on the no stat thing was these days - because as I said, years ago it was considered a no-no.

Thanks and heck, it it does work, I may still make it back to Brooklyn! (I was on the Belt last week with my regular car - wasn't pretty ... )

Archer

 

whats in a thermostat you need to use a saw for?? i dont understand that! why not just put it in a pan of water with a thermometer and see what temp it opens up at if at all. and yes running a thermostat can keep a street bound engine cooler than one without.as gtx said

 

1966 -

Apparently not in my case, at least not so far - I'll keep you posted.

Archer

 

i agree with gtx and fury you should run with a t-stat but hey thats only my opinion good luck

 

maybe getting airlock in the coolant system? what i do when i install a thermostat is drill a hole at about 3/16. so it can get the air out.. some stats have a cheap oneway valve already in them for that reason.

 

1966 -

Just a couple of things. I was always told / taught to run with a thermostat, so this is (hopefully) a temporary "fix". The car ran cool for the better part of a year, until last week. I was using a Mr. Gasket Hi-Flow 160 t-stat, and it seemed to do the job.

Still going with the assumption that given the age of the engine and how long it's been sitting prior to the rebuild, we weren't able to get all the rust out of the block. That was pretty evident with the manual flushes we already did.

Anyway, we see how it goes. I have a new t-stat sitting on the passenger seat as we speak.

The reason for the thread, was that I was actually a little surprised at how well it ran without one, even in "normal" street traffic.

Thanks

Archer

 

ive seen ppl go without them with luck.. if it were me id overheat at the 1st stop light.. lol

 

Gents -

Thanks for all the input. Just as a follow-up, a new 160 stat is back in and he engine is happily chugging along at 160 -170 in so-so traffic, Guess the flushing worked - at least for now.

Archer