Overheating?

[WarrenG]

My 289FIA has approx 1900 miles on it. Equiped with 1965 289 stroked to 331. Last night on my way home after driving approximately 25 miles and 40 minutes I thought I caught a whiff of coolant. When I looked at my temp gauge, it was up to 240-245 degrees F. After approximately 1-2 minutes it quickly dropped back to its normal 180. Approximately 15 minutes later while accellerating from a stop light, it moved back up to about 225-230, then within a few seconds quickly dropped to 180 again. This happened three more times with the top out at between 210 and 225 degrees. With the exception of the first episode, each time the peak never lasted for more than about 30-45 seconds and the gauge returned to normal operating temperature in less than 1 minute. For the last 38 miles and 45 minutes of the trip, mostly on the capital beltway, the temperature remained normal.
Other than the water temp everything else was normal. Oil temp remained between 175 and 185 degrees and pressure at 45-55 psi depending upon RPM. It was about 10PM and the air temp was probably around 70.
Upon shutdown, I checked the engine compartment but didn't find any sign of leakage however there was only about 1/4-3/8 of coolant in the Hamilton overflow tank.
Any ideas what might have caused this before I start taking things apart? My first guess was faulty thermostat, but was wondering if a faulty sensor, gauge or wiring might also cause the indicated fluctuations. Any help here would be appreciated.

[jwoodard]

I had a similar situation with my Lone Star Cobra when I owned it. After much checking I determined it was a faulty ground in my dash wiring. You might start there and make certain your ground for your gauge is good.

[DonC]

After you check the gauge and sending unit check the fan belt. Sounds like the water pump may not be doing all it should for you.
DonC

[strictlypersonl]

Since it's a mechanical gage, I doubt whether that's the problem.

I would suspect (in order):

Air in the system. Bleed any air from the highest point - probably a fitting in the intake manifold.

Bad thermostat.

Bad water pump.

[WarrenG]

Thanks Bob. I'll start on that tonight. BTW, since I'll probably have to add some coolant, what coolant mix do you put in the cars? Do you recommend any wetting agent?

[patrickt]

Warren, do you remember when I posted a note to you on the CACC forum to keep an eye on the connector plug to the left (driver's side) of the radiator that is the hot feed to the fans? On my car that plug was put together as correctly as it could be put but it still had an intermittent fault so my fans would sometimes come on and sometimes not. It finally culminated in my engine overheating and throwing up all over the garage floor. Before you go to any extravagant remedies, double check that connection; it’s always possible there was a batch of faulty ones that got through the ERA QA tests. Do this: With the engine off, throw the fan bypass switch on the dash so your fans are running, then wiggle the connections that are just to the left of the top of the radiator almost under the fender well. If you can get any sort of interruption in the fans by doing this wiggle test then you’ve found the problem. Instead of replacing the connector I just cut and soldered around them. Even with my stroked and bored FE, I run at 85-90 Celsius on 95+ degree days - even in stop and go traffic. Usually closer to the 85 mark, and that’s for both oil and water.

[WarrenG]

Patrick, I'll check that too. The fan was operating when I got home. Not sure about while on the road, couldn't hear much over the exhaust and the other road noise.

[Rick Parker]

I had the exact symtoms: fast rising temps after thermostat opened, temp gauge would swing wildly and peaked at 230-240 within a few seconds and then the gauge S/W mechanical would swing down to 140 and start the process over. Mine was on a fresh build. 289Hipo with the aluminum waterpump without a backing plate (1st generation). I had not run the combination previously. I fought it for several months, but the solution turned out to be a different waterpump with cast iron impellor instead of "sheet metal type", the one being used was a rebuilt unit from an Auto Parts store. The pump was apparently cavitating. I ended up purchasing a OEM Ford pump. No problem since then.
I will assume yours has run OK without prior issues(?) until this point. Check to be sure your pump is still functioning (impellor tight on shaft). Check your head gaskets.

[Dwight]

Not more than a 50/50 mix, but less antifreeze is better. Water (distilled) is more efficient at removing heat. I noticed that you live in the North. If your Cobra is exposed to temputatures below 32 degrees, you should check the ratio to be sure you are protected during very cold weather. Most Cobras are stored inside during winter months and do not need a lot of antifreeze to protect them. Too much antifreeze makes a Cobra run hot. We know this from experience.

Dwight

[strictlypersonl]

Warren,

For your conditions, I'd use about 1/3 antifreeze (0F freezing point) for its anti-corrosion additives. You engine shouldn't come close to straining the cooling system, but if you sit in traffic a lot, some Water Wetter might be good.

[patrickt]

Originally Posted by Rick Parker

I had the exact symtoms ... the solution turned out to be a different waterpump with cast iron impellor instead of "sheet metal type", the one being used was a rebuilt unit from an Auto Parts store. The pump was apparently cavitating. I ended up purchasing a OEM Ford pump.

Warren, as I recall Joe L. built your engine -- I doubt he slipped up on this point. He's only built a couple of million of these engines....

Additional thought -- It occurred to me after I originally wrote this that if you have 1900 miles now on your new turnkey build then you really should adjust the clutch. It has properly seated itself now and has changed from when Doug put it together. Keeping your TOB happy requires the proper clearance; it's a pretty quick adjustment. If you'd like, I'll post pics outlining the procedure.

[WarrenG]

Originally Posted by patrickt

Warren, as I recall Joe L. built your engine -- I doubt he slipped up on this point. He's only built a couple of million of these engines....

Additional thought -- It occurred to me after I originally wrote this that if you have 1900 miles now on your new turnkey build then you really should adjust the clutch. It has properly seated itself now and has changed from when Doug put it together. Keeping your TOB happy requires the proper clearance; it's a pretty quick adjustment. If you'd like, I'll post pics outlining the procedure.

Joe assured me that my pump was a Ford OEM when he installed it. He's pretty sure it's the Tstat. Thinks air in the system should have shown up sooner. I'm will check both. Actually, I'll just change out the Tstat. It's never made sense to me to put the old one back in even if it bench checks OK, because there have been a number of times that Tstats bench checked OK and didn't work upon install. I'll just keep the old one for an emergency spare.
I adjusted the clutch linkage this weekend to change the pedal height, but since I have a hydraulic clutch, I didn't think that there were any other adjustments. If there are, please post pics so I can see what I should be doing before I start it.

[patrickt]

When I say “adjust the clutch” I mean adjusting the slave cylinder to clutch fork clearance so there is no unnecessary pressure on the throw out bearing. As your clutch disc breaks in the clutch fork will move closer to the slave cylinder (with a “push slave cylinder” like we have), so you have to adjust the clearance on it. 1900 miles is a good time to adjust it since it’s probably nicely broken in now. Here’s how to do it:

1) Here is a picture of the slave cylinder on my ERA, yours is probably identical. Note the return spring, the silver looking locknut that is on the threaded rod coming out of the slave cylinder, and the brass colored fitting that is on the rod next to the locknut and that actually contacts the clutch fork.



2) Remove the return spring and back off the silver locknut and brass colored fitting about a quarter inch or more towards the slave cylinder. You will need two half inch wrenches to do this. One to attach to the lock nut or the brass colored fitting, and the second to go around the nut that is on the very end of the threaded rod behind the clutch fork. You hold that nut to prevent the entire rod assembly from just rotating as you try to unscrew the nut or fitting. Use your finger and push the end of the threaded rod back in to the slave cylinder and you should now have an obvious distance (a quarter to a half inch) between the brass colored fitting and the clutch fork. The clutch fork is now in its natural position with no pressure on the throw out bearing and the brass colored fitting is not touching the clutch fork.

3) Use your fingers and tighten the brass colored fitting until it is tight against the clutch fork. Put a .063" feeler gauge between the silver locknut and the brass colored fitting and tighten the silver locknut so there is a .063" distance between the locknut and the fitting and the fitting is tight against the clutch fork. Remove the feeler gauge and tighten the brass colored fitting back up tight against the silver locknut without moving the locknut. Thus there is now a .063" distance between the fitting and the clutch fork and the locknut is tight against the brass colored fitting. Put the spring back on.

[WarrenG]

After getting all the parts I might possibly need, I checked the cooling system tonight. Coolant was about 1/2 gallon low. Topped off with a 2/3 distilled water-1/3 coolant mix with one bottle of water wetter added. Then pulled the heater core valve since it was the highest point on the manifold to "burb" the system.

Started up the engine and ran it until it reached operating temp. Fan cycled on and off as it was supposed to as did the thermostat. Couldn't get it to go over 185. Cycled between 175 and 185 the whole time.

A few minutes after I put it back in the garage, I found a puddle of coolant on the garage floor. The asphalt outside where I ran it up had just been rained on so I couldn't tell if it dropped any coolant while running. Found fluid leaking from one of the lower radiator hose connections. Clamp was loose. Tightened it up. Hope that takes care of it. Will find out this weekend.

[Jim Holden]

WG:

Ah, the joys of being a shade tree mechanic.

Hope you have your problem solved. I find doing a "nut and bolt" check every so often to be prudent. A bit of the old English sports car walk around check before and after a trek is always a good idea too.

Jim

[WarrenG]

Originally Posted by Jim Holden

WG:

Ah, the joys of being a shade tree mechanic.

Hope you have your problem solved. I find doing a "nut and bolt" check every so often to be prudent. A bit of the old English sports car walk around check before and after a trek is always a good idea too.

Jim

I'm still getting used to reliving my MGB ownership days.

[Dwight]

When I was running a 5.0 EFI the water was always low when I checked it. The car would idle for 20 - 30 minutes and not overheat. This past winter I installed a 354 stroker kit in my motor. It still runs low on water but when I idle for 3 - 4 minutes the temperature will climb to 210. I think I have a problem with the adjustable fan control.
I just got back from the London Cobra Show. I have about 2200 miles on this motor and over 19,000 miles on the car.
Dwight