changing water pump and thermostat

[iowasparrow]

I've got a Chevy 366 with an AT545 trans in my bus, on hot days the motor get's overheated. In fact last week we had steam come out. I'm guessing either the water pump is shot or the thermostat is not working. I'm just going to get it done with and replace both of them. Question is, where is the thermostat located on this engine? I have not had a chance to look for it yet so if any of you know where I might start looking that would be great, also ever change a water pump on one of those motors? Looks to be fairly straight forward, pump is easy to get to.
Thanks,
Grant

 

[frank-id]

Chevy big block

Big block engines need a big radiator. I think your radiator is not doing a good job of getting rid of heat. Sounds like you are just guessing on how to solve a overheating problem. Do not throw money at an engine repair. Some times ya gotta spend a few dollars to determine the overheat problem source. There are lots of good radiator shops on the net.
The symptoms for a bad water pump would be the unit leaks, makes noise or the unit does not circulte any water. The thermostat can easily be removed to check the operation in a pan of boiling water to notice part opening completely. The fan belts that power the fan are also very important. Removing the radiator for just a cleaning is sometimes, money very well spent. With a IR temp gun, after engine warmed, check top and bottom radiator connections and note temp difference. The art and skill of engine repair is not often learned on the net. Frank

 

[lapeer20m]

Wow! What a great post!

 

[Steve-SKO]

Yes, Frank has the right idea. I just went through this last week with my 1966 Tiger which was getting over 250 degrees F after just a few miles. It was a fresh engine and shouldn't be having problems. I took out the radiator and took it to a rebuilder who took it apart and dipped it in a solvent. He said the core was only 10% blocked but that is enough to make it worthless. He tried to rod it (which hopefully is all you will need) but it was really blocked good.

I had an extra core sitting at home which he also dipped checked for leaks and blockage (there was no blockage in this one). I put the radiator into the car and viola no more problems. The engine hovers around 200 but that is very good for a small british car with a small block Ford.

If you can take out and put back in the radiator on your own it will probably only cost you around $150 to get it rebuilt. NOTE: It will need painted afterwards, use the special Radiator paint (I buy mine from Eastwood.com) because if you don't your paint may work as an insulator and ruin all the work you just did.

 

[frank-id]

Off topic

Hey Steve, many moons ago, I put a Ford 289 v8 into a 1963 Austin Healey, an english small sports car. The can would really accelerate rapidly. The engine was just stock with a few speed goodies. The car would go like **** but not much stopping. The owner, a your guy, did a huge fast top end run on a city street. The car was going about 125MPH and ran accross an intersection and ran over the curb and side walk. The oil pan and auto trans were immediately removed. The car was junked. The car had a special radiator made that was about 5.5 inches thick, a very tight fitting fan and shroud, and the grille opening was enlarged with new entry farings. Just another spoiled rich kid. Ahh yes te youthful learning curve. Frank

 

[KC10Chief]

Don't forget to check your radiator cap! If it's weak, it won't allow pressure to build up in your radiator properly. Therefore, the coolant will boil at a much lower temperature and you can get steam. I still agree with the other posters about the dirty radiator, but just replace the cap while you're at it.

 

[frank-id]

Ahh yes the infamous radiator cap

Todays radiator cap is just another method of tricking the laws of physics.
Water at level on a normal day will boil at 212 degrees F. If the water is placed under pressure, theboiling point is raised 2 degrees for every pound the water cooling system in under. If a 15 pound radiator cap is used the boiling point will now be 242 degrees F. Raising te boiling point of a cooling system with a defective radiator will only make any problems greater. I advise folks with a bad radiator to NOT tighten the cap complely, so no pressure will build that will blow out any water. Filling any overheated cooling system should only be done after engine is allowed to cool for a while then water may be added while engine is running. The best coolant for most engines is 15% coolant and 85% distilled water. Every large vehicle should have a coolant filter, and diesels require special additives. Tap and well water are not good for cooling systems because of the mineral content in the water. Humans love hard water, but cooling systems become encrusted with minerals and the cooling of the radiator is affected. Frank

 

[iowasparrow]

I should mention that last summer the engine was getting hot and finally sprung a leak around the water pump gasket, I was on RAGBRAI and I needed the bus so I went and bought a high priced bottle of stuff to stop the leak, I never got around to fixing the leak properly.

 

[Steve-SKO]

I think that is another reason to get your radiator core cleaned up. It probably affected the water pump far less than the tubes in your radiator.

 

[iowasparrow]

Last night I took the belts off the water pump and found no play in the pump, it appears to still be in good condition. I was then going to check the thermostat so I went to drain a little water out of the radiator via the drain plug, nothing, no water came out, just some sticky white crap and some sediment that resembeled sand. It's barely a trickle coming out the drain valve. It looks like the radiator is plugged. I found a guy here in town that said he can work on it, hopefully he can rod it or re-core it.

 

[hoser-SKO]

I have a Chevy 366 with an AT545 trans and just took it on a trip out west I was running 65 mhh on a 97 degree day and the engine never got over normal temps even going up steep grades, my 366 looks like it has 2 thermostats just looking at the housing now would be a good time to test them.

On a side note the engine did not over heat but the shifter cable for the trans did, look at how yours is routed mine was 3" behind one of the header tubes the heat off the header must have been pretty hot on that 97 degree day because it melted the plastic housing off the cable, the cable still works but getting it into reverse is hard, I took about 15 ty-wraps and put around the cable to simulate the plastic housing that burned off.

Look at your cable if it is 3-4 " behind the header like mine make a heat shield, mine looked factory routed I assume they never intended someone to run the bus for 16 hrs straight 65-70 mpg and 5-10 miles at a time WOT never letting off the gas on the long up hill grades and going against a 15-20 mph head wind...

Good luck let us know what you find and details like cost and part numbers would be good for the archives.

 

[iowasparrow]

update, I took it to a radiator shop, they called me the next day and told me to stop down there. When I got there the guy showed me my radiator, it is full of holes (large holes) where the previous owner cut away the cooling fins and soldered the leaks shut. It looked terrible I can't believe it even held water. They guy who took it out said he only got around 2 gallons of water out of it. I'm having him get me a new one. $380. Damn.

 

[hoser-SKO]

update, I took it to a radiator shop, they called me the next day and told me to stop down there. When I got there the guy showed me my radiator, it is full of holes (large holes) where the previous owner cut away the cooling fins and soldered the leaks shut. It looked terrible I can't believe it even held water. They guy who took it out said he only got around 2 gallons of water out of it. I'm having him get me a new one. $380. Damn.

They cant recore your old radiator this is usually much cheaper than new, now days some "new" replacement radiators are made in china or taiwan and the quality shows .

Its the price that probably made the former owner skillbilly your radiator together in the first place...

When you get it home take off the radiator cap and put a few drops of liquid laundry soap in the coolant also put in about 3 table spoons of baking soda, the soap will remove the surface tension of the water the baking soda will kill any acid in the system or you can buy water wetter it does the same thing but co$t 100x more . Every time you change the oil remove the radiator cap and use a volt meter set to DC and check the voltage, red lead in the coolant black on the negitive post of the battery when it gets to 1 volt DC drain and change the coolant.

 

[the_experience03]

Ok....the voltmeter is a new trick to me, but sounds really intriguing. What exactly are you looking for? Is this some goofy way of checking the pH or something? Is this a cheap way to check the coolant additive? Please do explain so I can go check my coolant's voltage

 

[hoser-SKO]

Ok....the voltmeter is a new trick to me, but sounds really intriguing. What exactly are you looking for? Is this some goofy way of checking the pH or something? Is this a cheap way to check the coolant additive? Please do explain so I can go check my coolant's voltage

The acid in the radiator turns it into a battery when it gets to 1 volt its a good time to change it, by adding the baking soda it prolongs the process and extends the life of the coolant, the one volt thing goes back to the very early 80's when computers first started showing up on cars, when the voltage in the radiator got to around one volt they started having problems and the computer sometimes started doing goofy stuff, the fix is to drain and change the coolant, personally I dont like to throw stuff away when its 1/2 used up so I use the baking soda, I use the soap to break the surface tension, been doing this for 25 years it works great, no need to spend 100x more on some coolant system additive, keep the acid in check and you never need "stop leak" either, on average I get 5-7 years on a coolant change, if the coolant looks dirty or has a brown hue to it I will drain the system and change the coolant, if you put the coolant in a milk jug and let it set for 6 months all the crapola will settle ot the bottom then if you carefully pick up the jug and slowly pour it into another clean jug you can seperate the crap from the good coolant and use it again, I usually blend it with new 50/50 (distilled water only).

 

[the_experience03]

Cool trick I'm not going to worry about it in my truck since the coolant is slef changing (the head gasket between the #3 and 4 cylinders is basically gone), but the bus seems to be pretty darn water tight so I'm going to check that tomorrow. Thanks for the tip.

 

[hoser-SKO]

Cool trick I'm not going to worry about it in my truck since the coolant is slef changing (the head gasket between the #3 and 4 cylinders is basically gone), but the bus seems to be pretty darn water tight so I'm going to check that tomorrow. Thanks for the tip.

For the heck of it check all your voltages and let us know what you find.

 

[Ryan Grimm]

I commend the use of distilled water and coolant in the system; the distilled water will also have a VERY slight benefit in somewhat dissolving any mineral deposits left by other tap waters. Distilled water is cheap at around 50 cents a gallon.
ALWAYS use the recommended coolant, in the correct proportions, for your engine. A 15/85 mix of coolant and water probably won't do the job.

And be aware that letting old coolant settle, and reusing it, is probably not a good idea. If it was that bad to begin with, is it still worth the cost risk to your engine? Keep in mind that the water pump lube will also settle out, so you'll lose that benefit.

As for generating DC voltage in coolant, I've seen a phenomena in classic cars; the intake end of heater cores and brass tee connections corroding faster than the other parts of the metal. Apparently caused by coolant flow/friction/acid buildup, and the charge collecting on the first metal it 'sees', resulting in pinholes.
Was told to solve this problem by running a bare copper ground wire to the front end of any/all metal parts that coolant runs through, and grounding it to the frame. I like the baking soda/dish detergent advice, I consider that an excellent maintenance tip.

ALSO, be aware that some diesel engines require an additive to reduce internal turbulence and breakdown of cylinder liners due to engine internal vibrations...the ignition cycle causing the problems...can't remember where/when I read about this.

 

[oldog12]

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