Cooling fan tenion on an MC5

Dreadnought · October 02, 2016, 03:18:57 PM

Greetings! Does anyone know how to set the fan tension on an early sixties MC5? My bus is overheating and the fan belt is one of the root causes I'm trying to tackle.

My model DOES NOT seem to have the air pressure tensioner I keep seeing on MC8s and others. It consists of bolts, springs and washers.

Attaching pictures:

PorchPeople · October 03, 2016, 09:05:26 AM

You will need penetrant, a 3/4 open box wrench and two 1 1/8 open wrenches. Loosen the 3/4 esna nuts at the top of the retaining bolts and then adjust the jam nuts accordingly to tension the belt. Best to work them together to keep tension even. Add a dab of no seize to the threads when everything is loose.
Also the miter box sight glass should read half when the bus is level. 90 weight gear oil works fine.
On second look your jam nuts might be a bit smaller than 1 1/8.

Dreadnought · October 03, 2016, 01:13:42 PM

Thank you very much for your help Porch People. I just tried- but was unable to undo the bolts even after liberal application of Auto-Kreul. I'm scared of using an impact an rounding off the bolts. Probably more to do with my weakened state due to recent health issues.

I'm going to try to drive it to my mechanic. He needs to take the engine out to do yhe clutch anyway. It's 20 miles away, I may have to keep stopping every time the gauge gets to 190 deg F and then wait. Or I could try to keep the speed down to 30 mph (I think that may work).

Thanks

Iceni John · October 03, 2016, 01:45:28 PM

Are you sure that the fan belt is too loose? Overheating can also be caused by so many other things. When your bus is at the mechanic he should be able to determine the reason - radiator blocked? stuck thermostats? unsealed air gaps? slipping water pump impeller? constricted exhaust?

John

PS - I had the pleasure of visiting your namesake, the RN's first nuclear sub, when it visited Rotterdam in the 1960s. Very palatial compared to the usual scrotty smelly diesel subs.

Dreadnought · October 03, 2016, 03:04:40 PM

Quote from: Iceni John on October 03, 2016, 01:45:28 PM
Are you sure that the fan belt is too loose? Overheating can also be caused by so many other things. When your bus is at the mechanic he should be able to determine the reason - radiator blocked? stuck thermostats? unsealed air gaps? slipping water pump impeller? constricted exhaust?

John

PS - I had the pleasure of visiting your namesake, the RN's first nuclear sub, when it visited Rotterdam in the 1960s. Very palatial compared to the usual scrotty smelly diesel subs.

Hi John,

I'm not sure no, but I'm tracking down the most probable root causes and knocking them down, one by one if neccessary. There are no shutters (even though the book says there should be) , the radiators although not new, look in very good condition. A thermostat is possible- which is another one that needs to be tackled. When I drive it again around the block- I'll see if the radiators get hot to check that. I want to change the water pump anyway- they're about $350-500 but my mechanic says that if there's nothing coming out of the weep hole...
I may get a new one anyway, if the engines coming out- it probably wont cost a lot more in terms of labour to get a new water pump fitted. The cooling system holds pressure well.

My favourite Dreadnought was the one from 1906- 1915 from WW1. It didn't see much action but was a formidable ship and show of power for the British Empire. Sea Lord Fisher who comissioned it seemed to me a bit of a nut case though!

Scott & Heather · October 03, 2016, 06:48:29 PM

Take some pics of your radiators both sides inside and outside surfaces and post them. Also, how hot does it get? I mean are you passing over the 200 degree mark?

Sent from my iPhone using Tapatalk

Dreadnought · October 06, 2016, 06:20:00 PM

Scott and Heather thank you for responding- sorry for the delayed response.

The radiators are in good shape. I've attached pics of the inside- the outside are similarly clean, but my iPhone six started acting up so I couldn't get pics

Since posting this- I've ascertained that the thermostat above the water pump isn't opening. The radiators stay cold as do the piping above them and the piping directly below the expansion tank.

I've let the engine touch 200- may be a little more before stopping it and waiting. It will continue to go higher if I were to let it

I will limp it to my mechanic (I talked to him today) and he will tackle this and the clutch. Taking it to the mechanic will no doubt take several hours - even though its only 20 miles away!

He speaks highly of 2 stroke Detroits, which contrasts a lot of the opinions I hear online