Fv721 fox

[Jeff Yost 0]

Why does my fv721 fox overheat at about ten miles?

[Diana and Jackie 10]

Why don't you have the service manual?

It's the first thing anyone buying a MV should get after buying the vehicle.

If you don't have the manual (provided you can get one), and there are plenty available for the Fox, then you will have a problem looking after it and resolving problems.

[sirhc 21]

You’re not giving us much to help us help you out!

[robin craig 11]

Jeff,

 

I am going to ask all the stupid questions to you so we can eliminate some causes.

 

Have you first paraded your vehicle? Was the coolant level up?

Was the Oil level up?

Was the fan belt to the blower volute bevel box in place?

Do you have a manual

Where in the world are you located?

What is your ambient air temperature?

What altitude are you operating at?

What mix of coolant to water are you using?

What gear are you driving in at what speed?

How long have you owned the vehicle?

Has it ever run at the normal operating temperature, ever?

 

 

 

[Jeff Yost 0]

Located in Michigan, US. Takes about 10 miles of 50 mph and it over heats. as it did for previous owner. Had a mechanic drill a little hole in the thermostat like the original  but didn't fix it. Lots of anti freeze. 

[sirhc 21]

Have you bled the air out of the cooling system?

[Diana and Jackie 10]

Lots of antifreeze? how much is lots ? is it 50/50 ? because if its more than 50/50 that maybe the cause.

Get a device for measuring the ratio and do a proper check.

Diana

[Jeff Yost 0]

I will check anti freeze ratio. How do I bleed air?

[andym 21]

http://www.greenmachinesurplus.com/cvrw-fox-125-c.asp perhaps?

Andy

[sirhc 21]

There is a bleed point on each radiator, just undo the bolt and wait until water comes out. There is also one on the water pipe which goes across the engine to the heat exchanger.

[Jeff Yost 0]

Thank you all for the feed back I will try the suggestions.

[Richard Farrant 23]

No one has mentioned the water pump drive belt yet, they were prone to failure in service.

[Starfire 11]

Did you get it sorted?

[Jeff Yost 0]

no. My plan is to remove the 2 radiators and send them to a shop to have them roded.

Thanks 

[Jeff Yost 0]

I had radiators checked and all is good. Is it possible of a bad pressure relief valve.

[Jeff Yost 0]

On the last test run after approximately 10 miles it reached 200 degrees and I stopped. The radiator covers were very hot. The engine covers were only warm.

[terryb 12]

Jeff,

If the rads have tested ok, then  its one of 4 things;

lack of coolant-fill header to brim and bleed air out with engine running at temperature.

coolant flow insufficient-water pump/drive belt/coolant passage blockage

Insufficient cooling air flow through rads-rads fins blocking air flow? fan moving enough air? all plates fitted ?

headgasket failure- run on fast idle with header tank cap open   and filled to brim-are bubbles/coolant  coming out on hard acceleration?

 

[Diana and Jackie 10]

And a thermostat seized closed

Diana

[terryb 12]

Just to add, I asked my colleague who drove a fox this weekend to a show, who said his gauge was showing 185-190f. 

[Jeff Yost 0]

This time I didn't stop at 205 degrees only being a couple miles from home. It rose to 220 when I stopped and was boiling when I shut it off. Then went to 250 not running. It lost only a few drops of anti freeze. Does this mean anything?

[sirhc 21]

Jeff,

Have you checked all the things previously mentioned in this thread?

Can you post a photo of the rear of the vehicle?

Chris

[Diana and Jackie 10]

Remove the thermostat and I'd concur with Chris

Diana

[Jeff Yost 0]

Have not tried all suggestions.

[sirhc 21]

You have all the right bits in place so that’s a good start.

[Richard Farrant 23]

31 minutes ago, Jeff Yost said:

Have not tried all suggestions.

Jeff,

just looking at the photo you posted. The silencer / muffler looks like it could be reproduced item. If it is not made correctly inside it could create back pressure and the restriction will cause overheating. Can you confirm if it is a copied part?

regards, Richard

[Jeff Yost 0]

How do I know correct/stock muffler from repro?