Water Temp

[rzayas66]

I have read the other posts on water temps, but I want to verify that I should not be too concerned. I have a 79 MGB that I just converted to a V6 60 degree, 2.8 with a carburetor. If I idle for 15 minutes or so, the water temp gets up to about 215; if I start running the car, I am seeing around 225. The timing is on, the radiator is the original MGB radiator, and the headers get a lot hotter than I am used to seeing on a small engine toyota.

I have a 195 degree thermostat, and I have no leaks in the system.

Should I be concerned about the operating temp? When I hit the engine head with a IR thermometer, it reads around 220 after running for 20-30 minutes.

Thank you,
Ron

P.S. I know I opted for an older, smaller 2.8 because it was readably available, so I could have put more power under the hood, but I have to tell you I am loving my MGB so much more with the new engine and 5 speed. Love this conversion.

[Bill Young]

Ron, what type of gauge are you using? I'm using the original Smith's gauge in my Midget which has a 2.8 MPFI and a stock MGB radiator with electric fan. No temp degree markings on the gauge, but it usually stays pretty well around the normal area and the fan's are set on a 212 degree thermostat and don't come on until the gauge is nearly up to the hot mark. I suspect that either the gauge isn't calibrated properly or perhaps your timing is retarded a bit. Retarded timing can cause these engines to heat up more than usual as I found out after replacing a worn timing chain and not retiming the distributor. The inital timing was off almost 15 degrees and the computer couldn't compensate for that. Retarded timing would also cause the exhaust gas to be a lot hotter than usual, which would account for the high header heat you mention.

[rzayas66]

Bill:

I bought a new electric gauge that hooks up to a new sending unit; it has a temperature reading gauge, unlike the original Smiths. I replaced the original one in my car because I could not get it to work with the S10 engine, and for $20, figured what the hell. Also, my electric fans are wired to run all the time (I was going to change the sensor, instead of cross-wiring it like the PO did, but figured their is no harm in having the fan run all the time).

I will check the timing again. I am using the timing setting that is in the manual for that engine, but your description of a hotter exhaust is dead on. Also, the starter hesitates a little on start up (although it check out fine when I had it on the bench), and I seem to recall that symptom being a timing issue also. I will give it a try and let you.

Thanks.

[mgb260]

Mixture may be lean or vacuum leak also.

[mgb260]

delete

[ex-tyke]

A good check of the gauge accuracy is to borrow or buy (from HF) a laser temp gun and verify temp at the thermostat housing. - my gauge/sender correlate very well with the laser gun readings.

[scot abbott]

A fair number of people seem to do OK with the BV6 and stock B radiator, but some people have troubles. Often the radiator needs a good cleaning and/or scale removal. I was going to use my B radiator, but the radiator shop said it wasnt worth servicing. I bought a brand new 1965 Mustang radiator for the 289 V8 for $134 delivered, and it was a simple install. A few adjustments and a set of mounting brackets I made.

[Jim Stabe]

You didn't mention what fan you are using. If the car runs at the thermostat temp while in motion but heats up when you stop, you don't have enough airflow from the fan. Get a fan from a Taurus V6 and your problem will go away.

[rzayas66]

Sorry for taking so long to respond, got sidetracked with work.

I made sure the timing was dead on (it was off) and topped off the fluid at the thermostat housing. The car is running better, but still running at 240 or so under speed. An IF reading at the thermostat is showing 220, but it feels hot. I think the issue is the radiator is not up to the task. Was originally going to see about getting a dual core in my MGB radiator, but may go with Scott's 65 mustang radiator. Any one else recommend a good radiator swap?

Jim: To answer your question, it runs well now at idle and in stop and go traffic, it overheats when I get it up to 80-90 mph on the highway (which is, of course simply the speed limit in Southern California). The fan I am using is the original MGB fan, but I have it set to run continuously while the car is on.

Thanks for the help so far, and I will report back after I have the new radiator in place.

[DiDueColpi]

Ron,
Turn your rad fan off.
It becomes a restriction to airflow when its running and the car is moving at any significant speed.
Up to 30 - 40 mph or so the rad fan can keep up but above that the airflow through the rad is higher than the fan and it blocks it.
Install a proper thermo switch for the fan and make sure that you are running a good quality thermostat.
Give the air a way out of your engine bay and you'll probably be fine.
Cheers
Fred

[rzayas66]

Good advice Fred. I will try that this weekend. I can rig up a switch to test it out at high speed and kill the fan.

Thanks,
Ron

[Anonymous User]

Hi,
Water temp to the unit effects production..
I really don't know, but I'm going to wildly guess somewhere between 180º-210º
thanks

[rzayas66]

Mike: not sure what you meant by your post. Can you explain?

Update: I replaced the fan switch, so the fan comes on and off as it should. Also set up a kill switch and turned it off manually after getting up to 75mph on the highway. Car still got up to 240. I am leaning towards getting a dual core put into the radiator (found a shop that will do it very reasonably). I just don't think it can keep up with the needs of the 2.8l or with the high heat put out by the headers.

[rficalora]

Ron, you seem focused on more radiator capacity -- but if "it runs well now at idle and in stop and go traffic" as you noted above, I don't see how this can be a capacity problem.  Typically long stints idling & stop & go is where the system is harder to keep under control.  It sounds more like an air flow problem to me.

[DiDueColpi]

I agree Rob,
most likely the air is trapped in the engine compartment with nowhere to go.
That would explain the headers seeming to be too hot.
 No airflow to cool them off.
The heat output from the headers has nothing to do with heating the engine up.
If they are too hot it's a symptom of something else such as timing or fuel mixture.
A thought just struck me.
And it actually hurt!
You are running with the hood on aren't you?
It's a vital part of the "B's" airflow.
Check out some of the threads in here about cooling.
Lots of really good ideas in here.
Cheers
Fred

[BlownMGB-V8]

Here's another thought, timing can have a dramatic effect on engine heat, and especially header heat. Could it be that you have correct timing at idle therefore no heat problem, but not enough advance at cruise, therefore extra heat there? Retarded timing will really make it run hot.

JB

[rzayas66]

Fred: yes the hood is on. A couple of things I should note, especially to jim's point:

I am certain that the timing is right at idle but not sure how to check if it is advancing correctly at speed? Do I need a dyno for that, or can I rev it up and look for a specfic setting? While the water temp stays good at idle, the headers get hot almost immediately, so I do think (after reading some other posts) that either my mixture may be off. What is the best way to check the mixture? I should note that I am experimenting with adding a cold air induction system (mostly for space) or finding the right drop air filter, and have been running without an air filter while I test drive the car. Could this be making it too lean and thus run hot?

Thanks,
Ron

[denvermgb]

There are a number of things you could do in combination to help with cooling.  The above suggestions, and:

1) Make sure you have a shroud for the fan.  It can significanlty help with air flow in the right place - through your rad. Make sure the seal and area around the rad direct the air flow through your rad.

2) Header wrap - can lower engine bay temps.

3) Add water-wetter to coolant.

4) Make sure radiator fins are clean and unobstructed.  This goes without saying to make sure the inside of the rad is cleaned.  It might not hurt to take it in to a radiator shop be cleaned out.

5) Perhaps look at adding an oil cooler.

I hope one or some of these ideas might help.

Good luck!

Brad

[rzayas66]

Brad: Thanks for the additional things to look at. The shroud is in place.   I am going to try the header wrap this weekend, and I am working with the carb to see if the mixture is too lean (the carb that is on there now was computer controlled and does not allow me to change the mixture setting). I get the feeling that it is too lean and heating up the headers too much. If taht does not work, I am going the have the radiator cleaned. Thank you

[BlownMGB-V8]

Header wrap is a mixed bag and if used long term almost always does more harm than good. Short term, for a vehicle that is only driven on nice days and never put away wet, it may work out OK, but the stuff holds in moisture, promotes header rot, and can cause stainless headers to crack. It is amazing how quickly it can destroy a clean new set of headers. I'd think twice about that myself.

JB

[rzayas66]

Thanks, Jim. Let me try the carb first. I am feeling that the mixture is too lean and driving the temp of the headers way to high (I am installing a non-compuer controlled Holley this weekend). After that, i will see how engine heat is affected. Will keep you posted.

[mgb260]

Ron, Make sure you get all the air out of the cooling system and check the intake manifold bolt torque. I drilled a 1/8" hole in thermostat flange when I had overheating problems in our Cherokee.  Went to 180 degree thermostat. Finally changed water pump when i noticed a little seeping out the weep hole. On the MGB make sure all the air goes through the radiator,not around it. I am going to put  either louvers in the inner fenders or duct air from the holes in the inner fenders to outside side vents. Good luck and let us know how you resolve the issue.

[DiDueColpi]

Hey Ron,
It seems that you are under the impression that the heat from your headers is causing the engine temp to go up.
That is absolutely not the case.
Your header temp will routinely be in the 1200- 1400' f range.
If they are getting too hot, this is a symptom of something else.
The headers are not making your engine overheat.
They are hot because your engine is overheating.
You said that you are running a computer controlled carb. If it's running without the computer it will be too lean for sure.
Make sure that the timing marks on your crank are accurate. GM engines are notorious for miss aligned marks due to a balancer ring moving around and or the wrong timing tab.
You haven't made mention of any pinging. With a lean engine running hot you should hear a ton of it, if the timing is correct.
As Jim said don't wrap your headers. It's an absolute disaster for a street vehicle. Even cast iron manifolds turn into junk very quickly when wrapped.
Cheers
Fred

[rzayas66]

Jim & Fred: I burped the system and made sure there was no air in the system last week. I have a 195 degree thermostat (read that the 195 actually helped keep the car cooler than the 180 in real world performance) and have checked its performance and it opens correctly. I have drilled an 1/8" hole in it. I do have a concern that with the new engine and the stock overflow tank, the overflow tank is no longer the highest point on the system (the thermostat housing is). Not sure how vulnerable that makes the system to trapping air.

The new cab will go in this week, and I will recheck the timing. I do not get any pinging, but I have a lack of power from the engine. It seems to lack power on hills, another reason I assumed it may a lean mixture. I will deal with the mixture and recheck the timing, do a pressure check to make sure the system is sound (there are no visible signs of leakage), and then see how it runs. It seems that if none of these help, I have to investigate a new radiator (or more likely a multicore replacement).

I will let you know early next week. Thanks again.
Ron

[rzayas66]

Finally got this all squared away. the issue, as many of you stated, was timing. The real issue was that since the distributor was computer controlled, and the computer is not installed, there was no advance on acceleration. I realize I should have known that. Anyway, put in a Weber (non computer carb), and a vacuum advance distributor and along with having a much faster and more powerful car, the overheating has gone away.

Thank you all for your help.

Ron