The Stovebolt Site Forums The Shop Area Engine Shop Engine over heating

I got my 235 back from the machine shop recently, got it put back together with the help of a mechanic buddy of mine and set it back in the truck. We got it running and are pleased with the way it sounds/runs, but the temp goes too high and it over heats in about 10 minutes or so. My buddy says that he will put a timing light on it tomorrow, that that may be a problem, or it may be that the used radiator (pressure checked only) may be restricted and not getting good flow. Anybody have any other suggestions or things that should be checked. The engine was completely rebuilt and the shop is a reputable one. I'm getting a little nervous at this point and anxious to get this thing running right so I can get the body back on the truck. Thanks for any help.Bill

What about the water level in the radiator ? Does the top hose get hot to indicate the thermostat is opening ?

Yes, we even swapped the 180 for a 160 thinking that might have been the problem.

Bill, did it heat up enough blow out the overflow or is the guage just on the high side?Did you drive the truck?

Yes it blew out the overflow. And no it isn't drivable yet. Its a COE and we wanted to get all the bugs worked out and be sure the engine ran good before I set the cab back on the frame.

Bill,

Couple of questions for you... When you say "overheats", does the radiator cap open up and let off pressure? Or, are you just watching the temp gauge? (You might want to buy a mechanical temp gauge and re-check.) Stock radiator, 7lb cap? Since it sounds like you've got the bodywork off, are you running a fan? Are you sure the thermostat is not up-side-down? What about your exhaust system, stock? If so, is the heat riser opening when the engine warms up? How many times have you fired up you new engine? Also, have you re-adjusted the valves?

Keep us posted,

That happened to one time. I thought the radiator was full but a big air pocket was in the block.The air cam out after the heater hose was lossened.A week ago there was a post on drilling a hole in your thermostat to bleed air.Just a thought.

64K10, We have a mechanical temp gauge hooked up and it reached 220 both times we had it running before we shut it off. My buddy picked up a new cap after the first firing, but I'm not sure if its 7lb. The fan is running and the exhaust is hooked up although not stock. I would hope that the t-stat is right side up but wouldn't swear to it. The heat riser is open, in fact its stuck in the open position(looking for a replacment manifold set-up for this truck) and no the valves have not been re-adjusted as of the second time we got it running.

I don't quite understand not putting the money down for a professional recore or quality new unit after spending so good money on the engine. :confused:

I'd bet you anything that the radiator is your problem. A recore or brand new 3 or 4-row radiator will fix your problem. Been there, done that

I didn't recore the old radiator because the only shop around wanted 600.00 plus to fix the original. I bought the used one from Carters that had supposedly been checked out and pressure checked for around a buck and a half, well the rest is history. I know I should of had it flow cheecked. As far as a new one?, I had a difficult enough time tring to find a decent used one for a 46 COE.

Take out the thermostat and drill a 1/8 inch hole in it. Start it up again and see what happens.. You may have a pocket of air, especially after filling a new, dry motor..

Thanks Bill, I will definately try that tomorrow when I get home from work. Thanks to all for your help.

If you are going to open up the thermostat housing, maybe it would be a good idea to check the thermostat. Place it in almost boiling water and see if it opens.

Or, run the engine without a thermostat just to see if the system will overheat without it.

Bill, the rad would have to be really bad to let the engine overheat sitting in the shop. If it over heats real soon after start up you probably have a blockage, like a stat froze closed, or upside down, or the water pump isn't moving water. If you pull the upper hose off the housing and don't see the pointy end of the stat, it's in wrong. A bleed hole will help with the possibility of air pockets. You could pull both upper and lower hose off, block off the lower hose outlet, fill it with water, then remove the block from the lower outlet. That will give you an idea of the flow through the rad. Mike

Bill, the rad would have to be really bad to let the engine overheat sitting in the shop. If it over heats real soon after start up you probably have a blockage, like a stat froze closed, or upside down, or the water pump isn't moving water. If you pull the upper hose off the housing and don't see the pointy end of the stat, it's in wrong. A bleed hole will help with the possibility of air pockets. You could pull both upper and lower hose off, block off the lower hose outlet, fill it with water, then remove the block from the lower outlet. That will give you an idea of the flow through the rad. Mike

When I first built the 39 I had a problem like yours.... it was two things... first bad thermostats after several I finally gave up and made a a blanking plate with some holes in it.
Next was 'block filling'...It didn't! I used the sqeeze the lower hose to pump the water through the block.

I've now fit a hose from the back of the head to the thermo housing to let the hot water purk from the back of the head instead of pushing it out the overflow

Your motor is heating up so quickly that you may have all these problems too

Even when you get it right the water will still find it's own level if the rads too full

Good luck

Jim's gonna love this one:

When I rebuilt my 235 the first time, I set the main journal clearances too tight. I cranked it up for the cam-break in. The oil pressure was really high, like 50-65 PSI revved up. Also, the temp gauge layed over to HOT in a matter of minutes. I shut it down, let it cool, then did the cam break in again.

The engine ran great for 300 miles, until the #2 and #3 main journals wiped down to the copper. The crank seized up and that was all she wrote. :o

Chip

Chip I don't LOVE to hear this kindda thing!
That's why I have suggested a later motor.

In my life building all kindsa engines I can count the ones I've lost on one hand....no cause I'm good but because I am CAREFUL and LAZY.....check everything real close,many times....cause I don't want to do it again.

Jim, that ain't being lazy, that's working smart. Makes the best use of your time and money.

You may not have one, but the infrared hand held thermometers work great for this type of problem. You just point and read. Find out real fast how hot the radiator, block, or head is. you can even tell when the thermostat opens by checking above and below it. You might check into one. Joe

I realize that the motor was just worked on, and there's a lot of solid advice on that, but what about the radiator? Have you flow checked it to see if it's in spec?

Don't forget to start with the obvious.

You can feel around by hand on the radiator core to check for cooler spots (don't burn or maul your hand)
A cool spot indicates a clogged passage.

I use the infrared handheld thermometer to check for hot/cool spots all over the engine.You can find possible blockage SAFELY!

Well I had a few minutes in between all the other stuff going on and heres what I came up with so far. I did a low tech flow check by removing the lower hose and running the garden hose in the top of the radiator, and water came out the bottom as fast as I could put it in the top. I realize this doesn't eliminate the possibility of a flow problem. Then I drilled an 1/8 inch hole in the
t-stat, put everything back together and fired it up. In about 12 minutes at a fast idle it had reached 200 degrees so I shut it down. I am going to try removing the stat and tring to release any trapped air from a plug on the t-stat housing next. The machine shop questioned the water pump, even though its brand new and suggested having he radiator flow checked. I will keep you all posted and thanks again for all your help.Bill

Could the impeller on your water pump be cavitating? Are you running the correct size pulleys? Could the wrong impeller have been used on the pump causing it to not pump water? Did you leave out the stiffening spring on the lower hose? It keeps the hose from collapsing under the suction of the water pump.

Bill, et al...

I think this might be a stretch but... What about the head gasket? Could the shop have installed the wrong one? OK anyone... I've never compared a 235 to a 230 / 250, are they close enough that one might be able to put a 230 on a 235? (Where the bores, pushrods, bolts line-up, but not the water jackets. Just thinkin' out loud, er... "on-line" here!)

Or even got it flipped around. Easy to do if yer not paying attention.

-Oyob

Well the verdict is in! It seems as though everyone was a little right but Mr Proffit said it best. It seeems to be a bit of everything. The biggest part was the mechanic installed the gasket backwards! We found this out after I had the radiator checked. It was fine, good flow. The water pump was checked and was fine. After doing everything to remove the elusive air pocket I insisted, with some argument, that we pull the head.
There it was. We installed the new gasket and reassembled all and when we refired the engine, would you believe it overheated again! I think we cured it though with timing and by removing air. I used Jims suggestion on air pocket removal and yesterday afternoon the engine ran for about 45 minutes at a fast idle and never it went over 170 degrees.
It seems as though we are still having a little problem with the timing. I will try to explain so it sounds as though I know what I am talking about. The mech says even though the engine runs great, good throttle responce, and good temp, the timing light says the we are around 13 degrees too advanced and he can't retard it any further. His question is if there is a difference between the flywheel on a 46(original trans, bell housing etc) and a 54, which is what the motor is. He seems to think the timing might be correct but the flywheel marks may not be right for the engine. Is the ditributor in right(my question)?
Hope this makes sense, remember, I am still just a glorified wrench fetcher, but after this experience am gaining knowlege every day.
Thanks again very much to all for your help. The Stovebolt Page and all you people are the greatest!!

I would drive the truck if you can. See how it feels out on the road. Does it ping or knock on hills, or over heat under a load. The timing number is not as important as how it runs. If it runs great at 10 advanced, then thats where you set your timing, each engine is a little different. Back when they were built, everything was equal, fuel, and compression. Now with rebuilds and different fuel per state, you have to set each ones to where they run best and not worry about the number. Drive it awhile and change the timing a degree or to every so often. Then you will now if it is right or not. Don't be afraid to try different settings. Joe

Bill,
Is your mechanic looking in the right hole? The hole for the timing marks is above the starter. There is one on the driver's side too, but don't use it. The "BB" is 5 degrees BTDC. All the flywheels are the same AFAIK.

Josh, we have the right hole. The timing still shows about 12 degrees off but it runs so nice. I won't know what it will do under a load for a while yet. I'm going to adjust the valves and hopfully set the cab back on the frame this week. Well at least it is not over heating anymore.