Two new radiators, still overheating

[Scott & Heather]

Buttoned everything up today and took her out for a test drive. She overheated. Wouldn't cool down. Went to the back and noticed hose clamp broke. Is my thermostat stuck and causing extra pressure buildup causing the overheat and clamps to blow and blowing my last old radiators?
https://vimeo.com/110160319


Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.

[Scott & Heather]

And can anyone give me a tutorial on replacing the Tstats? I assume I remove the four bolts on top of the housings?


Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.

[luvrbus]

Sounds more like a air lock or pocket to me if it was doing it before I would check the T stats and the seal inside the housing if that doesn't cure it check for a loose impeller on the water pump they are bad about coming loose if not locked with a punch.  

There should be a 7 lb relief valve on the surge tank for the pressure control maybe it leaked and someone removed it and plugged the tank

Watch the 4 bolts on the housings soak good with PB and take your time those will twist off then it is drill and tap time not much fun always try to tighten 1st then try to remove works the best for me  

[Nineforever]

Exact thing happened to me once a while back it was traced back to the water pump , replaced pump and thermostats and all was fine

[RickB]

Scott, buy or borrow an IR gun and shoot the inlet and outlet of the t stats, the radiators for cool or hot spots and the water pump. You can also shoot the exhaust manifold to see of you have a cylinder/head gasket issue.

Could've saved a lot of money a few years back when I was overheating if I would've suggested that to the mechanic who was dumbfounded as to why my motor was overheating.

Don't shoot it at reflective surfaces as it ill give you false readings

RB

[Scott & Heather]

I have a temp gun, so I'll fill with water, buying a new hose clamp right now and then I'll check to see if there are discrepancies in the temp before and after. Annoying because I just had it at ww Williams to ask about the overheat issue. They dynoed the bus and said it wasn't overheating. Frustrating because I can't limp it back to them if it's overheating so I'm stuck doing this myself with 2 weeks before we leave...


Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.

[luvrbus]

You just changed the antifreeze I would bet on a air lock a Dyno will heat one up in a hurry  ::)If it left the dyno not heating then it is a minor problem

[eagle19952]

sounds like an air lock to me too...quite common when you change 20 gallons of coolant...

find a way to bleed the system...
let it idle and circulate for as long as it isn't over heating..
did you change the coolant and simply drive off...
what did it dyno at... we need numbers ...

i would run the air out before i tore in to the t-stats....

[harpold700 3]

Make sure all your seals around the rads and air box are in working condition.

[Stormcloud]

Just a thought.......check that the fans are firmly secured to the shaft on the blower assembly.

A local friend has an MC-2 that has rubber isolating bushings in the blower shafts on his bus.
One of the rubbers had failed, but you couldn't see it. Both fans seemed to move air down over the engine just fine at idle; but one of the fans was essentially freewheeling when it came under load ( increased rpm ).

Bus ran fine up to about 50mph then would start heating. He replaced thermostats and hoses with no improvement.
He somehow stumbled upon the loose fan and failed isolating block.

All is well after a $20 fix.

[digesterman]

I am betting on a air pocket, air expands a lot compared to water, thusly the broke clamp

[muldoonman]

Don't know if your engine has a valve and cylinder to control belt tension but on my 8V92TA had prevost service all fluids including radiator (antifreeze) and they left valve almost closed. Would run at low speeds but hit intestate at higher rpm and it would heat up and scared me to death. Limped home and my Tech found valve shut. Couldn't tell at idle looked okay to me. Slipped at speed. Just a thought.

[oltrunt]

I know that I am talking through a hole in my hat because I have never had one of your thermostats in my hand.  That being said, like others, I wouldn't be surprised to see an air lock.  Over the years I have seen that happen on a wide variety of vehicles--particularly those with a heater core higher up than the thermostat.  I now drill one or two 1/8" holes in every new thermostat flange and position them at the "top" of the housing to help burp the air.  Not an original idea as I've purchased several t-stats so equipped but it sure has helped.  I also pinch and release the upper hose as I fill the system to encourage a good burp.  Jack

[Scott & Heather]

Thank you very much all of you. Chasing this down... And taking all the advice. I let the coach cool, I then opened the coolant fill door and it was under a lot of suction. I added three more gallons of distilled water. I then ran the coach up to temp and let it cool and added another gallon. The next time I started it and ran it I couldn't get it to overheat. But I haven't driven it yet, just left ebrake applied and let it idle under the "load" of the brakes. That overheated it the first time but after adding the 4 gallons of coolant I can't get it to overheat now. It was 75 degrees today just for reference. Tomorrow it will be 60 and I'll test drive it but I'm bringing several gallons of coolant and water with me. I bought a heavy duty tbolt type clamp to replace the broken cheapo worm clamp and it doesn't appear to be leaking any coolant now at that hose. The air pocket expanding and causing the burst hose theory makes sense to me. As for the air piston for the belt, mine is stiff and I have to manually pull on it to get full belt tension. How do I adjust the air cylinder pressure? Also, I do need to finish installing all the radiator seals. Tomorrow I'll make that happen, test drive and see what comes. I'll also check for loose fan cages. I've checked them before and they didn't freewheel but I'll check again. Thank you again guys. You're a great group and I'm thankful


Sent from my iPhone using Tapatalk. Clumsy fingers may contribute to mistakes.

[eagle19952]

7 gallons is a lot... did you lose any on the overheat ?