Sprinter 316 help needed urgently.

[Roadrace]

Hi guys,
I have a 316 sprinter, used it last Sunday and ran faultlessly. Been sat all week and I wanted to do some work in the back tomorrow (I'm kitting it for bike racing), so I backed it on the drive ready. Thought I'd leave in running a few mins as I had the lights on chucking some stuff in the back. After only a couple of mins the fan kicked in ! Jumped in and selected the temp on the dash and it was close to the top ! Turned it off, checked the coolant etc and the hoses barely felt warm ! Circulation ? Thermostat failed ? Took the covers off, accessed the thermostat, took it off and poured boiling water in the assembly, no movement what so ever even after a good few minutes. So I thought I would wedge it open a little, try it, if it was better I would order a new one etc. Re-assembled it and ran it with the airbox off for a min to check for leaks etc, a few mins later and it's hot again ! With the added bonus of the engine management light now on. Put the air box back, plugged it in and decided to move it back off the drive to find it's now in limp or similar. Any advise ? No noises, grumbles or rattles.

 

[StMarks]

Well, obviously it sounds like your thermostat is faulty if you subjected it to boiling water & it didn't even start to move.?
Have you tried running it with the thermostat removed for the time being, or am I being too simplistic.?
The EML light on my Vito "trackday transport unit" re-set itself when I tripped it by wrongly connecting a sensor & then corrected it. I think it took a few cycles before it went out though iirc.

More importantly, what's the bike.?

 

[Roadrace]

As I said above I wedged it open as you can't remove them, they're a sealed unit. Just seems really odd that it ran like clockwork, there are no noises etc yet the sudden temp issue.
I have raced everything road and off road but retired a couple of yrs ago, my son has just started MX.

 

[toolman1954]

Hi,
May I suggest you take off the drive belt and try to turn over the water pump by hand. Can you feel any resistance or see any displacement of water.? Perhaps the pump body has separated from the impeller and now there is no water going around the system.
Steve.

 

[Roadrace]

Hi, thanks for the reply. That was my plan in the morning, I pulled one hose tonight and turned the motor and nothing came out so I presumed the thermostat was stuck shut. Took off the housing and tried to activate it with hot water, didn't see any movement so I thought I would wedge it open as a "quick fix" to see if that was the issue before ordering a new part. It was the same ! Was going dark so decided to wait until tomorrow, I didn't realise the stat doesn't have a bypass hole in it but separate bypass circuit as part of the housing ? Will check circulation with a hose off and also with a hose to check for a blockage, the coolant is crystal clear with no signs of dirt / corrosion.