The Stovebolt Site Forums The Parking Lot Big Bolts "MoTater's Gettin' HOT

Last Monday, I was taking "MoTater" for a "quick"(52-55 M.P.H.) run,to top-off the tank. "she ran good all the way into town,(about 7-miles),but after about the 4th mile,on the return stretch,the gauge jumped from mid-point to 3/4. By the time I got to mile 5,she was just about "pegged". I pulled her over until "she" cooled-down,then made the last mile or 2, in the "safe" zone. I replaced the thermostat yesterday, thinking that it was the problem, but after driving about 8-miles,"she" over-heated again. I had the head rebuilt about 4-years ago,and haven't had a problem,until now, but "she" hasn't "seen" any highway miles until Memorial-Day Week-end. Then it was about a 100-mile round-trip,with no temp. issues. Does anyone have any ideas? Thanks in advance!! B.T.W.-'55 2nd 6500,235 head,261 block-HAS PROPER HEAD GASKET INSTALLED

Is it actually boiling over, or is the gauge just indicating "hot"? Try using an infra-red thermometer to confirm that the coolant is actually getting close to the boiling point. The most common cause for overheating is exhaust gas getting into the coolant, from either a cracked head or a leaky gasket. A dirty radiator is another possibility.

If there is a shop nearby with a 4-gas exhaust analyzer, ask their diagnostic tech to hold the exhaust sampling probe over the radiator filler neck with the cap removed. If the "hydrocarbon" reading goes up dramatically, it's a sure sign that exhaust is getting into the coolant. Just be sure NOT to get the probe down to the level of the coolant- - -it really does nasty things to expensive internal parts if antifreeze gets sucked up into the machine!
Jerry

i had that happen on my 1978 GMC pickup, and i found out that the radiator cap was on too tight and didn't let it breathe..........i had to replace it and now it is fine. i also replaced the coolant in it. hope this helps you on your quest.

I have exactly the same thing right now !!
ORdered a new thermostat friday, will change it today or tomorrow.
In my case it's after a water pump change, so I hope it's just air pockets.

Will try to empty the coolant, and refill. Trying to find a hagh enough spot to be able to get the air pockets out.

But I am afraid it can be the mixture of 2 differant coolants, which I know is bad, but I didn't know what type they added in US so I had to just try. Will remove all, run with water once only.

If that works I will refill with new coolant. All from one supplyer.

That's CRAZY,Ulf! I Bought a new "old-style" radiator cap,and I HOPE that works. The
"New-style" is 4-P.S.I.,(on truck now),and the old-style is 7- P.S.I.. If that doesn't work,I'm going to check the water pump for blockage(s),and completely flush and drain the radiator/cooling system. Hope our problems are not serious. These trucks of ours are like kids... they always need something to behave the way they should. HaHa!! Good luck!!-Bill

Hey,gang! Went out to work on "MoTater" today,and flushed the radiator...(also back-flushed)...added water...test drive with new "old-style" radiator cap)...now "she over-heated in 1/4 of a mile-compared to 8-10 miles like last week. I removed the thermostat housing,and lower hose,and circulated well water (with the engine running)...just a trickle coming out of the water-pump,until I shut the engine off,then it GUSHED out. All I can think of is that something got into my water jackets (probably head and block),so here I am...back where I STARTED 5-years ago...pulling the head. Only good thing is...I already replaced the valves and installed the hardened seats. Adjusting the push rods AGAIN,is something I'm Not looking forward to...(Engine needs to be at operating temp. to insure correct adjustment). I also removed the water pump and found absolutely nothing wrong. I'll keep you posted on the "operation". Thanks to all for your suggestions

couple idea's that are probably stupid, but I have seen it happen so just to be redundant......thermostat in the right direction ? and are you sure your water pump is turning the correct direction ? ( not that they made a serpentine belt setup for these, but I suppose it is possible the rebuild shop may have grabbed the wrong impeller )

again I dont mean to insult any ones inteligence by offering seemingly obvious solutions.. but some times its the simple things.

Dan

Dan, not insulting, I have the same problem after replacing my water pump, and I thought about if the pump can have a wrong angled impeller already. How to find out, just do everything allover again But I will start with a good FLUSH, a replacement of thermostat and hope for the best, will of course check with water in thermo level without the belt on to see if I have a blown gasket.
But a head gasket replacement might be needed. Time will tell.

Well... I found the problem...after troubleshooting "everything",before I pulled my PERFECTLY GOOD HEAD/GASKET..My problem was...a mouse nest that was overlooked in the radiator!! When I first bought "Tater",there was a hole worn in the lower radiator hose,where it rubbed on the front cross member. the evidence of said nest didn't rear its ugly head until I drove the truck-hence circulating the fluid enough to cause a clog in the radiator. After 4- years,the head looks like new,so do the pistons/cylinder walls. Not even a ridge on the cylinder walls!! Now for the TASK of "Buttoning "her" back up. You can adjust the valves "cold",by adding.002 to your tolerances. This helps, since the last time I did it ,my assistant got hungry 1/2 way through the job,and by the time we got back, (20-30 mins.),the engine cooled enough that I bent 2 push rods on the 1st start. I hope none of you have to go through all of this work for nothing, so have your radiator checked BEFORE you decide to pull your head,or be like me... BALD,from pullin'your hair OUT!! "See-Ya"!!

O.K.-Here's what's going on so far... I got the radiator back. I put the head back on. I got the intake/exhaust bolted back on. Plugs/wires are back on. Radiator/water pump thermostat housing/fan/pulley installed. Plug wires/distributor/coil, back "together". Vacuum lines are tightened down,as well as fuel-line. Basically,everything is ready for initial start-up,(except,of course,valve cover ...need to adjust valves,YET.) Which brings me to my next question in our never-ending engine mysteries... Plug wires are self-explanatory on my 261. Firing order:1-5-3-6-2-4,clockwise,right? Put cap on same way it was removed before tear-down. Now,when I try to start it,it sounds as if the engine is being cranked when excessively hot,or extremely retarded timing.(Like cranking with dead battery). I haven't been able to check my distributor (vacuum-advance),but does anyone have any ideas on something I,m overlooking? Thanks!!

if you rotated the engine while distributor was out you could have dropped it back in 180 degrees out. cranking sluggish check all connections to make sure they are clean and tight.

Thanks, kb3csw. Makes sense,but first thing I did was dis-connect the battery,to avoid anything like that happening. The only thing I removed was the coil (Un-bolted from block),and the distributor cap. But,THANK-YOU!! I will check all my connections. It may be that simple!! I wouldn't doubt that AT All! Going to work on 'Tater again,tomorrow. I'll keep you posted,maybe even make a video,IF I get 'er done!