Temp Reading

[Aaron]

Hello All,

I have installed a new thermostat in my 48' B1B, it took me awhile to find an internal bypass that would work. The one I got is from NAPA and on the thermostat it says 88 celsius which I think is about 190F.

Can someone please tell me what my temp guage should show on a normal 80-90 degree day?

Thanks, Aaron

[Aaron]

I just took the old girl for her first spin in 25 years since pulling it out of the weeds this past January.

The temperature guage really fluctuated between 185 and 212 which is maxed out.

Any suggestions?

[buds truck]

I would have the radiator flow checked and put in a new thermostat. Bud

[MBF]

I think a 170-180 thermostat would be hot enough. I'm running a 165 in my 1 ton and shell run up around 170-180 on a hot summer day. Given the fluctuation of a 60 year old temp guage-I'm good with that. It is hot enough that I'm buring off any condensation in my oil and its staying clean w my homemade PCV system. You may want to flush the block separate from the radiator to get rid of any accumulated crap in there so that it doesn't migrate to the radiator. Mike

[TodFitch]

I just took the old girl for her first spin in 25 years since pulling it out of the weeds this past January.

The temperature guage really fluctuated between 185 and 212 which is maxed out.

Any suggestions?

The one time that I had the temperature gauge really fluctuating was when there was no bypass flow. That meant when the thermostat was too cool to open the back of the block (where the temperature sensor is) got hot. Once the thermostat opens the back of the block cools dramatically.

[grey beard]

Aaron,

Have you ever flushed the water jacket in your engine block? When you open the pet cock drain valve on the left side of the block in front of the distributor, does coolant gush out or just trickle out? If the latter is true, your water jacket is in need of a major flush. I couldn't believe how much crud had accumulated inside the water jacket of my own engiine. If this is the problem, you could swap thermostats till the cows come home and the engine would still run hotter than normal. Pull the water pump and distribution tube, then knock out all the block core plugs and start flushing. I used a garden hose and an air gun with a long snout - got junk out for nearly an hour till it was all clean.

The other easy test you can perform at home is to pull the lower radiator hose off and block it with something solid, then fill the radiator. Once filled, if you remove the plug from the lower radiator hose, all the water should gush out in less than one minute. If it comes out slowly, or reluctantly - reluctant water? - your radiator core may be majorly plugged up. This is fixable at any reputable radiator shop.

Get the block water jacket clean and the radiator core clean, and I promise you the engine will operate in the normal range, even on the hottest days. JMHO:)

Lots of luck. Let us know how you make out.

PS Is your timing correct? Retarded timing makes engines run much hotter than normal - the combustion is still taking place on the exhaust stroke and heating up the head and manifold much hotter than it was made to tolerate. Check this out first - it's easiest to fix.

[Aaron]

Thanks for all the great advice. I had someone else tell me to check the timing too, so I think that is what I will check first. My radiator has a brand new core in it, so that should be ok. When I open the petcock on the left side of the block the fluid comes out readily.

If the timing isn't the problem then I will probably get a lower temperature thermostat and see if that solves any problems. If that doesn't work then I will pull the water pump and start flushing!

Thanks again, Aaron

[bach4660]

on a cool day, with a 165, the gauge reads 170, the rad reads 168,(measured engine side, motor off) spark plug #1 is 165, #6 is 161 and the exhaust manifold just for fun was over the 400 degree max of my gauge.

[norrism1]

Not for the faint of heart. I was taught how to remove the tanks on the top and bottom then clean the cores out, fix any splits and reassemble. Saves a ton of time and money. Cleaned the outside and painted black. Looked and works like a new radiator. Patients is needed to do this yourself. Had to plug a couple of tubes that were beyond repalir but that does not deminish cooling.

[Don Coatney]

Not for the faint of heart. I was taught how to remove the tanks on the top and bottom then clean the cores out, fix any splits and reassemble. Saves a ton of time and money. Cleaned the outside and painted black. Looked and works like a new radiator. Patients is needed to do this yourself. Had to plug a couple of tubes that were beyond repalir but that does not deminish cooling.

Please teach all of us how to do this on a honeycomb radiator? I have done this on straight core radiators but never on a honeycomb radiator.

[grey beard]

Hey Don,

Ya gotta' be quick - to get that honeycomb to stand still when it see's the rod coming. On second thought, mebby you could use a honeycomb rod . . . . . . .

Actually, top and bottom tanks are a snap to remove, A friend once showed me this trick and it works quite well. Just use your propane torch, heat the tank seams slowly and use compressed air to blow the melting solder off. Gives you a perfectly clean solder seam you can put back together with solder after you clean it with acid.

Straight tube cores are easy to clean, and if they're from old stuff, I'd rather do the job myselfr than have someone do it who really wants to sell me a new core, if you know what I mean.

Try it sometime.

[norrism1]

Don, I was talking about the straight core not the honeycomb. Gotta remember to add the little bits of info when I type.

[bach4660]

Not for the faint of heart. I was taught how to remove the tanks on the top and bottom then clean the cores out, fix any splits and reassemble.

What do you use to fix a split, brazing rod? or just solder?

[55 Fargo]

South Dakota,weeds in January, didn't you mean the snowbank.........LOL

Great to see another old vehicle on the road again, I hope you have a lot of fun with it...........The Rock

[55 Fargo]

I posted this a while back, another member was having acute overheating with his old flattie.

180 T/stat will start to open at around 176 to 182, and should be fully open at 200 degrees.

What temp are you running at?

A good temp should be around 180 to 195 .

A 160 T/stat begins to open at 156 to 162, and should be fully open at 180 degrees.

Is this what you are running at?

Even if you run a 160, and other problems are creating a higher engine temp, ie, clogged water jackets, plugged water distribution tube, or poor flow through the rad, defective water pump, late timing, and a heatriser stuck in the cold warm up position, can all exacerbate high engine temps and will elevate engine temps in warm summer weather.

Around town, high temps or when idling in slow traffic, a fan problem may your cause, highway speed high engine temps can be a rad in poor condition, or a lower rad hose that is collapsing, and/or a waterpump impellor that is not pumping coolant.

So give us some more details, then possibly we can assist you with the problem............Fred

I also posted this message.

Here is a number of items that require attention to have this engine run at a decent temp w/o overheating.

-clean rad with good flow and the ability to dissipate heat, particularly important at highway speed, and when ambient temps outside are hot.

-fan belt tight, fan in correct position for maximum flow, especially important in slow city traffic at speeds under 35 mph.

-water dist tube, needs to be free and clean

- water jackets pronounced clean, remove side freeze plugs, clean out, flush every hole you can.

-correct waterpump in good shape and working

-rad hoses in good shape, especially the bottom hose

-160 to 180 t/stat, drill small hole in lip, to allow air to escape when filling system.

-correct engine timing, correct point gap

- heat riser, not stuck in cold warm-up position to allow hot exhaust to circulate to intake, rather than exhaust freely.

- brakes not dragging.

If all of these itmes are functioning in good order, you should be okay, if not something is amiss if you overheat and boil over.

If your current outside ambient temps are over 85 daily, then you may run hotter under the hood, a good target is 170 to 190, even the odd time up to 195 or even 200 is not going to be critical, it's when you start climbing to 205 210, that the trouble begins.

A 50/50 mix of antifreeze will raise the boiling point to 220, a pressurized rad will add 3 degrees for every 1 psi of pressure.

-warmer climates, ie Arizona, California, 75% water 25% antifreeze would be fine

You want to keep it under 200, it's best if it could be maintained at 185 degrees, your engine will run cleaner and more efficiently.............................Fred

PS I hope this info is of some use to you............Fred

[Aaron]

Great information...

I am running a 190 degree thermostat (NAPA 381-190), and I took it out for a couple miles yesterday in 80 degree weather. The temp guage held around 195 to 200.(hard to tell exactly with the original gauge)

From what I have read this apparently is pretty normal considering the degree thermostate I am running.

I have a new radiator core, it is a non pressurized system, checked timing yesterday and was fine.

Would I be better off with a 160 degree thermostat, especially when running the truck in 95 degree weather or hotter?

I will have to take it out a few more times and keep a close eye on the temp, but from the looks of it, I may not have the problems I thought I had.

[55 Fargo]

Even if you run a 160 t/stat, it will quickly warm up to 160 in your hot weather, then it will climb to it's level, if it runs at 185 on hot days great, even up to 195 won't kill it, but keep it below 200..............Fred

[norrism1]

(quote) bach4660- What do you use to fix a split, brazing rod? or just solder?

Just solder, if really bad, cut tube in two, clean inside and out, flux and solder. Propane tank with flux, 60/40 solder worked fine.