coolant temps now reading high at idle

[resq302]

Ok, while I was out in Gettysburg, my engine was starting to run hot when it was idling.  Temps were getting up to 210-220 at idle but then went back to around 180 while driving.  That weekend was hot and humid.  Since I have gotten home, the temps have been around the 12 oclock needle position (200-210) driving and while at idle gets up to 220 and sometimes almost to the 230 mark.  The only thing I have done to this is adjusted the timing to try and recurve the distributor.  I did fill up with 93 octane out in Gettysburg at a Hess station so it is possible that I got some bad gas or some gas that has a different formula than the Hess station in my town.

One thing I noticed also is that the paint on my valve covers are starting to blister on the sides where the HP exhaust manifolds get close to it.  It has never done this before in the life of the car since I have owned it.

Here are the details on my car and engine... The car is factory stock with the exception of a MP electronic ignition conversion kit that was installed in 2003.  The factory 22" 053 rad was recored Sept. of last year with a high effeciency 2 core radiator.  The cooling capacity of this core is equal to a standard 3 core rad.  There is no fan shroud as the 22" 053 rads that cooled the 383 big blocks and were backed to a manual tranny did not get one, nor a fan clutch.  The fan is the factory 7 blade fan also.  I just replaced the 180 degree thermostat with a Milodon Hi Flow thermostat rated at 180.  Still no change.  The engine has a restoration MP purple stripe cam (Ron has the specs on it) and the engine was rebuilt in 2001, bored 30 over and boiled out also.  A coolant pressure check had the needle hold steady at 16 psi so if there is a leak, it has to be a very small one and internal as I can not locate any leaks outside of the engine.  I have also not had to add any coolant or water to the radiator either.

Does anyone have any insight to this?

Does anyone here on the board have a 053 radiator without a shroud and has their coolant temps running cooler than mine?  Does yours get hot at idle and then cool off when your start moving?

Any help would be appreciated as I do not want to cook my motor or do any damage to anything. 

Thanks in advance,

Brian

[BMOTOXSTAR]

It was super hot & really humid last week at a local car cruise in Solon,Ohio.
It was packed and cars had to sit and wait for about 15 minutes for people to cruise through, to get a spot. Allmost everyone had to pull over or shut there cars off. I know that my temp gauge started to creep way up on a 73' HP 400 BB. Everone in line was bitching how there cars had never heated up like that before.
It must have been the heat and thick humidity,  maybe our cars are not use to the humid weather?
It has to be global warming .

[is_it_EVER_done?]

Resq302: Since you state that the car cools down as you start moving but heats up at idle (or very low speed) proves that you have deficient airflow at idle.

The addition of a shroud will probably cure your problem since you are not getting enough airflow at idle/low speed.

Even when these cars were new, the 22" radiator was only barely adequate, and only in temperate climates. Add overbores, years of corrosion, etc., and you can have problems.

However, the fact that it shows whatever temperature on the gauge is no indication of overheating. First of all, factory gauges will always show a lower temperature than you are actully running so that everyone is happy with how cool the engine is running, but the rule of thumb is that if it's not "puking" coolant, it's not hot. It is one of the worst myths that the internet perpetuates that an engine should run at 160, 180 or other sub 200 degree temperature.

The reality is that 195 should be minimum for anything other than a dedicated race engine and 210 to 215 is ideal as the best compromise for power vs. engine longevity as the engine wears nearly 3 times faster at 160 vs. 200. This has been tested, studied, and proven beyond any contestation, but I'm sure some will contest it anyway.

So if your engine isn't boiling over, and it's not pinging at the higher temperature, forget about it. Otherwise add a shroud, and you should be fine.

[resq302]

The problem is that it just started doing this.  It was never like this before.  Out in Gettysburg, when I was moving, the car got down to about 180.  Now I can not seem to get below 210 range.  Yes it is nto puking coolant, but that could be that it is below where it will force the coolant out of the overflow hose.  Also, I have NEVER blistered the paint on my valve covers before.  To me, this means that the engine temps are getting WAY to high.  Finally, the exhaust manifold paint is turning white in spots where it used to be nice and freshly painted look of cast gray paint.  This also leads me to believe that the exhaust temps are getting hotter than normal.

[Just 6T9 CHGR]

You said you adjusted the timing etc.....doing that you might have leaned out the carb etc...put the timing back where it was and then check it

[deputycrawford]

     I would definitely re check your timing. You mentioned that it runs hot at idle and the valve covers are blistering. To me that's tell tail sign of timing retard. I believe much of your combustion burn is happening in the exhaust. Advance your idle timing around ten degrees and let it idle for a few minutes. Don't drive it, just let it idle. If it runs cooler, pull the distributor and start over in there.
     Oh, and get a shroud on that thing. I believe you need to create negative air pressure through the radiator with the shroud so it pulls the air through.  A fan clutch would be better yet, but the shroud is a must.

[resq302]

I put the timing back to 10 degrees at idle and it still gets hot at idle.  It also pops out the carb when you floor it from idle at 10 degrees.  Funny thing is, it seems to get hot at idle at any degree of advancement.

I am probably going to get a shroud for christmas as my parents were hinting that.  However, prior to is sudden change, it was running fine without a shroud.

[blue69]

I had a running hot at idle problem for four years that I just fixed. I tried almost everything (put the original fan in shroud on, replace thermal with non-thermal clutch, put a new thermostat, checked radiator hoses, pressure test, set timing.....). The only thing that helped was the non-thermal clutch which lowered the temp about 10 degrees. This year I replaced the stock water pump with a 440 source pump that puts out 40 gpm. I also used a mix of water wetter and antifreeze for extra insurance. It works great now and never goes above 180 degrees even on the hottest days with the a/c running. This is on a mild 440 with 3.91 gears and a modine 26" 3 core radiator.

[firefighter3931]

Brian, as mentioned above the cooling system apperars to be inadequate at lower engine speeds when the car is stationary. The high ambiant temps you're experiencing is also contributing to the problem. Looks like a shroud is in your future.

I don't see the timing being an issue at this point....unless you were running 30* at idle which you are not. It should be fine with 12* base timing as we discussed.



Ron

[resq302]

Ok,everyone, I think I might have found the problem.  I decided to do a coolant pressure test today with the engine cold.  Sure enough, once I got up to 16 psi. I noticed a puddle start forming under the K-frame.  The fast drip seemed to be coming from the water pump area.  I left the cooling system in tact and removed the fan and pulley to see exactly where it was coming from, either the gasket or the pump shaft.  It was leaking from the weap hole on the bottom side of the pump.  What I am thinking is that with the engine moving faster when I was driving, the circulation was enough to keep it cooler, however, when I was at idle, the pressure was building up and letting it vent out of the weap hole causing the temps to rise at idle.  Again, below 16 psi, it did not seem to leak at all, or that much that it was noticeable.  At pressures above 16 psi, it would really start to leak.  Strangely enough, the leak did not show itself when the engine was hot.  Maybe it was leaking just enough to let the pressure off and only bleed out a small amount of coolant?  Who knows.... now the fun comes to try and find a water pump, paint it, and install it before my car show tonight that my local town has.  Can we say NASCAR pit crew speed?

[resq302]

Well, the new water pump did not solve the high coolant temps.   It still gets up to around 230, but since the new water pump, it takes a little slower to get there.  I am almost wondering if somehow the idle circut is to lean or something with the carb as it only seems to be a hot idle condition.  This is really driivng me nuts as I have basically replaced between last year and this year everything in the cooling system.

[MR.MIKE]

I have the same problem     I know you read my thread
going to play with the timing next - i will let you know the results !!
mike

[69XP383]

Hey Brian,

I was just thinking, I forgot to mention in the p/m about the temp. sending unit. Did you try replacing/testing your temp sending unit? A friend said he had three sending units for his 69 coronet and he tried all three units in the water pump, each had a different reading on the guages (15 degrees difference from the lowest unit to the highest unit), and he had a fourth that was not working at all. I just bought one from Auotovalue and installed it on the high flow pump I bought from 440 source...I think it cost about $12.

Brian

[resq302]

I have a mechanical sending unit that I am temporarily going to hook up and see.  I know the engine is running hot cause I have blistered the paint on my valve covers.

[resq302]

Ok, I think I might have found the problem.  I installed a mechanical AutoMeter coolant temp gauge today and checked it compared to the original electronic factory gauge.  When the mechanical gauge was reading 180*, the factory electronic gauge had the needle at the 12 o clock position which is probably around 210*.  I drove the car around and it rarely went above 190* while moving.  At a traffic light it crept up to 195-200* but fell as soon as I started moving again.  After returning home from the drive, I let it idle and after about 10 mins, the temp was up to 215-220* on the mechanical gauge while the factory gauge was reading 250*.  The outside air temp was 87* with 67% humidity.  Needless to say, not the coolest of day.  I had also swapped in a rebuilt Carter AFB Competition carb to make sure that my factory carb was not running lean.  Thinking that the sending unit was bad in the factory gauge, I swapped it out for another one.  Same readings. 

Can anyone recommend a good gauge restoration or repair shop?  Does anyone have a good working coolant temp gauge they would be willing to sell for a 68-70 B body with rallye cluster dash?