Engine heat in GM V-6

[DonB]

I'm struggling with heat issues with 3.4 GM.
New engine, radiator, water pump etc. Equiped with A/C but NOT used.
 
Concerned from the begining about engine heat, we installed an electric twin fan, shrouded puller, added a 9X13" smaller radiator plumbed into the system and mounted horizontially behind the front valance.... to add more Sq. inches of radiator surface. It has a seperate fan as well. Additonally I am also running Evans coolant (@$40 a gallon). Space between rad and front mounting pannel is fully shrouded to direct air flow thru the rad.

The 600 miles across Kansas to Colorado Springs required multiple stops to cool thing down. Each time we stopped for gas, the heat would rise from 190 to 220+ with engine off... and stay there. Best way I can describe is a slow steady "ratcheting up" of the indicated heat.

 However, we found that 15 minutes or so, if we would start the car for 30 seconds and then shut off, the heat would start to drop. 2-3 "applications" would return us to 180-90 and off we'd go again. Came home the 600 miles the same way. It was as if we needed a way to circulate and extract the "hot" water from the block, thru the rad but with the engine off!

After checking the thermostat, I replaced after drilling a small hole (per suggestions) to allow for any air bubbles. No apparent improvement.

Heat guage has now "died" and may have been the real culprit but... temp readings with laser heat gun seemed to confirm readings. Will be replaced along with heat sensor.

Options offered to date:
low cost/no cost

Increase space between A/C radiator and engine rad.
Completely remove thermostat and test drive.
Remove hood and test drive

More rigous efforts

possible louvers in hood or ducted air out of engine bay
Replace new alum rad with a larger Ford at a canted angle to fit space

Anyone out there solved this puzzle before?
Thanks
Don B.

[Jim Stabe]

What radiator do you have in it? How hot is it getting and does it boil over? What kind of fan/shroud are you using? Does it get hot while running or when stationary? Have you sealed the radiator preventing air from going around it? Is the timing set properly and does the advance mechanism work?

There should be no problems cooling that setup so some pictures might help.

[Moderator]

I would install an entirely different temperature gauge and sender - even if only on a temporary basis - to get a second opinion. In fact, I'd probably do so with jumper wires, so possible wiring issues are excluded from the mix. I have a hunch that your cooling problem is really some sort of instrumentation problem.

I'm confused by this statement: "After checking the thermostat, I replaced after drilling a small hole (per suggestions) to allow for any air bubbles. No apparent improvement."  Do you mean that you checked the thermostat by suspending it in a pot of water on your kitchen stove? (That's the way I've always checked them.) The thermostat should be wide open above its rated temperature. And, if it opens up okay, I don't understand why drilling a small hole would help.

I'm familiar enough with the car to be confident you don't need a bigger radiator, more fan, better ducting or shrouding, or louvers. You're going to find a simpler and cheaper fix.

[Moderator]

Jim, specs of cooling system components and detailed photos may be found here: <a href="http://www.britishv8.org/MG/DonBonar.htm">Don's HIWD Article</a>   (I hadn't announced the article yet because I've been slow about hitting up potential advertisers.)

[BlownMGB-V8]

Don, I really hate to even mention this, but odd as it may sound the Evans coolant could be at least part of your problem. I know it isn't what you want to hear.

You might want to do a little more research on it though. From what I understand it cannot absorb as much heat as water, or even as much as a water/glycol mix. Less heat absorbed, less heat transferred.

Try to post a photo of your radiator shrouding and ductwork. Many problems stem from hot air recirculation through the radiator.

See if you can retard your timing a few degrees. Frequently that can help with cooling issues without hurting performance. In some cases advancing the timing can do the same thing. Rarely is the timing optimized for cooling.

Jim

[rficalora]

Each time we stopped for gas, the heat would rise from 190 to 220+ with engine off...

That just sounds like heat soak to me.  I'm not following what the problem is.  What am I missing?

[BlownMGB-V8]

Rob makes a valid point also. Where is the temp sensor located? (This is the justification for those applications where the radiator fan runs after the engine is shut off. Perhaps you might want to consider that.) Also according to Brian McCulloch these engines are quite happy running in the 220* range.

Jim

[RMO 699F]

Don, as we discussed at CS, the problem , whatever it is, is not one of refinement, but of basics in the system. I ran my 3.1 in my Mgb gt for years with the basic Mgb radiator and temps stayed @ 170. I would look at basics...is your water pump turning in the proper direction? I am not an expert in cooling and have been wrong about a lot of  analysis in the past, but it looked to me like you simply were not getting enough air flow through the radiator with the close proximity of the condenser in front of the rad and  large surface area of the shroud behind the rad...just saying...
Good luck Don!

[DonB]

Thanks to all for the comments and suggestions! For those of you who asked for more info or pictures... please go to Curtis' great work and photos in the HIWD section.

I'll check out every suggestion offered...

When first driven, my indicated heat readings stayed in the 170 to 190 range and I  assumed this was "normal". later I was told this engine type normally ran "hot" and tems of low 200s was very common. What say you experts?
Specifically...

Jim S.- Rad is new aluminum 9X18 off E-Bay... think Chinese manuf. It gets hot but has never boiled over. I'll recheck timing... think Pics will answer your other questions.

Curtis- (Thanks for the pics and article) My first thoughts were "bad Thermostat" so removed old one and boiled 4 times. It always FAILED to open and was my solution! Replaced and no change. Small hole in new unit was a "tip" from others that postulated it might be air bubbles trapped in cooling system and this would allow for release...and keeping warm water in the block in cold weather during start up is not seriously affected. New Auto Meter gauge and heat sensor on order from Jeggs as we speak. Yes, we'll jumper wire to test before I take that damned dash out again!

Jim B.- Please look at Curtis pics for some info you requested... I'll be talking with Evans folks today. I chose this product because of reported excellence in handling this very issue but I would dump it in a moment if indicated. Problem is... once removed and replaced with H2O, then entire system must be treated with yet a seperate agent to absolutely remove all traces of water before fresh refill. Total well over $100 just to test. I will kep you posted.

Rob F.- I have no engineering background so my understanding of heat soak is very rudimentary but that's what I thought... but while crusing back from Topeka SCCA races a week or so later, it rose from 190 to 240 in the length of time it took me to stop and pay the toll, engine and all fans running. Is this another clue?

Jim B again-  Here's new info for me... Brian's comments about 220 heat range! Sensor is located in front face of Eldlebrock low rise manifold.. just below and slightly right (viewed from the front) of Thermostat housing and return line to rad.

Mike M.- All good points... I cannot find paperwork to see exact model # of water pump used. Is there a way to confirm correct rotational direction without removing? Will double check serpentine routing against Bill Ds' setup as he built both... but reasonably sure it is correct but is it the correct pump?

Again, thanks to all for help and suggestions

Don B.  Hot in KC

[rficalora]

...but while crusing back from Topeka SCCA races a week or so later, it rose from 190 to 240 in the length of time it took me to stop and pay the toll, engine and all fans running. Is this another clue?

Well, that is[/i][/u], at least, very different than the temp rising after the engine is shut off.  If the engine is holding temps when you're driving at speed but climbs quickly as you come to a stop, it does sound to me to be air flow related.  I'm not sure, but I think if the water pump were rotating the wrong way, you'd be gettnig hot even when driving faster so I'd personally focus on air flow to start with... Mike's suggestion to get 1-1.5" space between condensor & radiator is a good recommendation.  Also check your fans.  Some will spin the wrong direction if wired opposite of intended... you might be pushing hot engine bay air through the radiator; that'd be the 1st thing I'd check.

I doubt it's anything requiring louvers or other air escape holes -- most of those are most effective at speed and the others might make 5-10% improvement -- e.g., they're tweaks to improve a marginal situation.  Like Mike said, you seem to have something more fundamental going on... something you'll say "Doh!" when you find it because it'll seem obvious when you do.

[BlownMGB-V8]

Curtis, do you have a link to his HIWD? I wasn't able to find it in the index.

Jim

[Moderator]

4th post in this thread...

[88v8]

The tip of drilling a small hole in the stat is good - my TR6 sometimes used to boil over explosively when I stopped after a hot run. Never could find the reason, but hole drilling stopped it.

If your car is OK at speed, then airflow through the rad and water pump rotation is likely OK. When you stop, you're depending on the water pump and, if necessary, the fans. However, the general under-bonnet heat is also critical. For instance, headers don't help, I'd never put tube headers on a car with potential cooling issues.

Rereading your first post, as Rob said, I don't actually understand what the problem is. Does it boil over? Because what you're describing is just what happens when you put a big lump of metal in a small space and get it all hot, and then stop the airflow that keeps it cool. The temperature shoots up, then when you move off it falls again. That's not a problem, that's just how it is.
You have a pressurised cooling system, it's designed to run over 212 without boiling.

I presume your fans(s) have been hot wired so they keep running with the ignition off?

When my car is really hot, the fan runs for a couple of minutes after shut-off. In my TR6, and in my Lightweight V8, I have a pusher Kenlowe with capillary sensor in the top hose, one can adjust the cut-in temperature if required.

Ivor

[BlownMGB-V8]

Very nice work Don. I love the creativity and the styling is quite nice. As expected the quality and workmanship is there.

As for the overheating, as mentioned everything does seem to be in place so either something is not working as it should or it's a matter of fine tuning. For that engine I can't really see airflow as being an issue and that much radiator looks like it should be sufficient. Personally I like to see a surge tank used on these cars as it adds some extra cooling and keeps any air out of the system but it looks like your thermostat housing is below your top radiator tank (true?) so it shouldn't be needed. Does your overflow bottle keep all air out of the radiator so that when you remove the radiator cap after cool down it is completely filled?

Another thought is your radiator cap pressure. You can perhaps bump that up a bit. If the system burps while running the temp will tend to go up so you want to prevent that. Because on a vertical radiator the water pump output pressure is added to system pressure, that system should run a higher pressure cap than a crossflow system. How much pressure does the water pump add? At least 3-4 lbs in any engine and higher rpm and higher capacity pumps have been known to add as much as 20 psi. and maybe more. Your limiting factor is probably the hoses or possibly the heater core but I would think you could run a 20 psi cap without worrying. That could help.

Then you go looking for small issues to fine tune. Timing, obviously and you may have to do some research on that engine and do some testing to find the optimum range. On the RM we had to reduce the advance for better cooling but when we did it we were running quite a lot of advance. Too little advance will cook the headers and add heat as well. We also found that under certain conditions the mixture went lean and made the engine run hot. In that case it was leaning out badly at low throttle and about 1500-2000 rpm and really putting out the heat. Things like that will overpower even the most extreme of cooling systems.

Jim

[MGBV8]

Gonna say it again, ceramic coated headers & y-pipe.

Doesn't seem the fans are getting it done. Could be that the radiator is smothered by the condenser.

[RMO 699F]

Don...a couple more thoughts...are the puller fans wired correctly and actually pulling?
Are the fans wired to a relay and getting the full amperage? Knowing Bill D did this setup I am sure these are moot points...but does not hurt to double check...

[DonB]

For Carl and Mike,
Thanks guys...

Headers are already ceramic and wrapped with the Thermo wrap. I went out both sides for ceramic coated side pipes below the doors. Only part of exhaust system not coated and/or wrapped are two braided SS couplings used to fit. Those are both below and behind the engine bay on each side.

Fans are "pulling" as designed and do run thru a relay. I'll double check amp reading.

New heat gauge should arrive today for temporary install. Will post results as we progress... keep the suggestions coming...

Not the sharpest knife in the drawer

[WernerVC]

Is it possible that the waterpump doesn't have enough flow ?
I have a friend with overheating problems on his 4 cyl B. He has changed to an electric driven waterpump.
Something to consider.
Werner

[Charles]

Don, ? what are the "T" connection in the heater hoses for?
Your engine and mine are the same, With a cool engine if you can look into the radiator neck and see in you can tell which way the coolant is flowing, mine flows from the upper hose into the top of the radiator. Feel on the upper and lower hoses, which one is getting hot first. The top hose on my engine gets hot first. As mentioned earlier you may have gotten a reverse flow water pump.

Regards
Charles L

[theonlyiceman53]

I can't really follow the flow with the pictures but is there any possibility the flow is short circuiting the main radiator via the small radiator?  Is it in series or parallel flow?   Drawing a small diagram might help to pin down any problems with the cooling system.  

 In some engines the hot heater hose flows from the pressure side back to the inlet side of the water pump so if the heater circuit is bypassed the hot engine water will re-circulate back to the engine without cooling it and give some odd temperature readings.  

Cheers,
Bill.

[burner1]

I concur with Jim on Evans coolant. I ran it in mine. It does not have the cooling capacity of a traditional 50/50 coolant mixture. In a normal system with more then adequate cooling you would never notice because the temperature is controlled by the thermostat. When the cooling capacity of the system is exceeded it begins to rise above the thermostat setting.

In mine, I could only go about 10 miles before starting to run hot. I put in an oil cooler under the front valance and I got quite a bit more mileage but still too hot after driving a while. I changed to traditional coolant and the system has since been fine.

[superdave]

I had a heating issue in my 70 MGB with 3.4.  I have a bigger aluminum radiator and single electric fan.  The temp would be fine while moving, but would creep up every time I stopped.  I ended up putting a small GT350 style hood scoop from Speedway that allowed that underhood heat to escape when I stopped and that helped a lot.  Different from your issue it seems, but something to think about.  Louvers would do the same thing.  I liked the scoop since my hood had a ding right in the middle and it allowed me to get rid of that and use a larger air cleaner.

[MGBV8]

Don,

Just curious to see if you have tried replacing the Evans, as suggested by Jim B. & Gary. I usually go with 30/70 mix of antifreeze/water. Doesn't get as cold here in Spring & Fall and I don't drive my B in cold, nasty weather on salt covered roads. Some may need the 50/50 for the extra boil-over protection, but mine doesn't run hot.

[denvermgb]

Don,

I know my expertise can't hold a candle to most folks' skills here, however....  Perhaps I missed something, as   I am trying to see where coolant is added to your system and where you bleed the air out?  On my car, I had to mount a coolant filler/thermostat housing because the rad sits lower than the engine.  Brad

[DonB]

Once again, thanks to all who offered up potential solutions on my heat issue. Some of you have also added PMs or asked specific questions. Here's a recap of what I've done so far... and future action plan when it's not 15 degrees in my garage!
Overstated.... it seems to come down to air flow, fluid capabilities, correct measurement, and a realistic "normal" heat range for a 60 degree V6.
 
Measurement- Installed new 180 thermostat, new Auto Meter gauge and probe, and will run a dyno test next spring on timing and lean/rich carb settings.  

Fliud- Will defer on dumping the Evans collant till spring. Once we have a baseline, I'll run it both ways.

Air flow- see below... tried to turn grill opening into a "cold air box" to drive all thru rad. If necessary, will also open louvered vent holes in inner fenders to wheel openings.
Again , thanks to all.  Don B.