BDA overheating

[ashyers]

It's a pressurized system with a coolant recovery tank as opposed to a coolant expansion tank. The cap on the T-stat housing controls the pressure in the system. Unpressurized systems have not been run for many, many decades.

 

Check the cap and do as John suggested with the hose in the coolant recovery tank.

[fastg]

I run a non pressurized expansion tank on my Honda power Locost without any problem. I would recommend an expansion tank that has a port at the bottom to make sure anything pushed out to the expansion tank is sucked back as the engine cools. 

 

Graham 

[BlueBDA]

I'm an idiot. Alternately, not being as hard on myself, I shouldn't make assumptions when I'm not with the car to look at things.

 

I get it now. Cap provides the pressure valve for the overflow tube, thus a pressurized system. Makes perfect sense.

 

So this weekend I will:

 

- Cut a new overflow tube that reaches the bottom of the overflow tank, cut on an angle at the end.

- Hose clamp that hose to the thermostat housing to allow the system to be able to suck overflown coolant back in.

- Drill a couple of small holes in my new thermostat.

- Install thermostat, fill with coolant, and try to get any air to burp out.

 

If it then maintains proper temp I can then replace thermostat with a higher temp one. I just got the 160F as I wanted every chance of not running hot. I suspect/hope that the problem I've had is just the old thermostat failing. Which BTW was also a 160F one.

[fastg]

Sounds like a plan, you don't need a hose clamp on the overflow tube as long as it's a snug fit, there is no pressure on that hose. 

 

Graham 

[SENC]

Remember that the thermostat doesn't necessarily impact the ultimate running temperature and it has very little to do with overheating (unless it is stuck closed or to high a temp rating), it is there to help the engine warm up to its designed operating temperature more quickly.  Early Sevens, mine included, didn't have a thermostat - they were open flow - a flow advantage once warm, but since coolant flow through the radiator initiates at start-up it does take longer to get to a good operating temperature.  Ie., there may not be a reason to put in a higher temp t-stat, unless you just want to raise the temp further before allowing coolant flow through the radiator.  And a lower temp t-stat will not prevent overheating, it only means the coolant flow starts earlier.

[BlueBDA]

Just closing the loop here. Installed my thermostat with small holes drilled, filled with coolant, put car on an incline to get my heater core lower, ran it, and temp stayed under 80C. Then did a track day yesterday. Temp did get up over 80 - maybe 85, possibly touched 90C, but no higher than that. I'm in second gear for much of this track, so I was revving the engine pretty high for much of my sessions, but had no issues. Will check the coolant level and pull off the nose to check the overflow bottle, but I think I'm good.

[Croc]

Thats great news Jeff!  

 

Which track were you running?  

[BlueBDA]

Thompson, CT. My "home" track. I've also been to Lime Rock and Canaan, NH so far this year. Palmer, MA next week.

 

I really liked Canaan. Small track with lots of turns. More of a Se7ens track vs a Porsche/Corvette/etc one.

[11Budlite]

Good news on the overheating issues Jeff!

 

I did the track day at Palmer this past Sunday.  Didn't have the Caterham quite done so had to take the Miata.  Palmer was a little more to learn than Canaan but a lot of fun!

[BlueBDA]

Back to this thread.

 

During the Sevens track days Sep 19-20 my car did great, but did still tend to run hot.

 

I just re-drilled out the two thermostat holes I had previously created, now to 1/8" diameter. The coolant did seem to bubble through those holes well when I added coolant. So we'll see if that helps.

 

In the meantime, I'd like to get a new thermostat housing cap, but am having trouble finding the right one. Note in the picture in my 7/8/21 post above how close it is to the cam cover, so the cap needs to have a smooth OD, without protrusions. Can anyone point me to the correct part?

 

Here's the best I've been able to find online:

 

https://smile.amazon.com/gp/product/B000C5BWX2/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

 

I'm not positive it'll fit, but for $12 it's worth a try. Reviews say it is a 16lb cap. I assume that would be ok to use. Any thoughts on that?