Water pump replacement

[Matchless?58]

Hi I have just replaced the water pump on my 3c11 . I also cleaned the rad inside and out and flushed all the system out . Replaced fan belt and did the usual thing of cable tying a spare belt around the pump drive coupling . All good so far . I then decided I might as well replace the thermostat while I had my maintenance head on . This is where I need to ask a question before I go any further .
Is it supposed to look like this inside the thermostat housing ? I ask because I've never seen anything like that before and i don't know if that's supposed to be there . I suspect not but I don't want to start pulling things apart until I've checked .
Have a look at the pictures and see what you think .

[Matchless?58]

Seem to have doubled up the pictures but you get the idea I hope

[gecko.cx]

Which engine do you have?

Just taking a guess here, but my assumption would be that when the thermostat is closed, that 'nozzle' would be open allowing water to circulate around the block.
When the thermostat opens, the nozzle is closed off forcing all coolant to circulate through the radiator.

Why there is a rubber hose, I have no idea, but the appropriate engine manual may shed some light.

[Matchless?58]

Hi its a 4/98 engine . Had a look at various manuels I can find on here but what I really need is a diagram of the engine and cooling system . Or somebody who has done the job before and has more knowledge than me ( not difficult lol )
Any definative answers out there ?
Cheers Chris

[essexpete]

Google Leyland 4.98 manual on ebay, there is a bit of a schematic diagram. Perhaps you can see the layout? Could not copy the link on my phone.

[Matchless?58]

Had a quick look on Google this afternoon . Could see no sign of my current setup so I am going to remove it and just install the thermostat . I think gecko might be on the right lines . The worrying thing is WHY was the thermostat removed in the first place unless its a cheap bodge the sort you use to get out of trouble then never bother to fix ? . I can't put the thermostat in anyway as that nut and bit of rubber hose is in the way so it's got to come out . I think I will keep a close eye on the engine when I first run it up in case it overheats . Couldn't do anything today as it was persisting down all day . Had a try out of my new welder in the workshop need to practice as next job is to weld up the bonnet of the machine .

[gecko.cx]

Apparently the thermostat has a large disc on the bottom that looks about the size of your rubber hose making this theory look plausible
https://www.charnleys.com/part/leyland_ ... mostat-88-

If there is not enough space to fit this style of thermostat, I'm wondering if a spacer is missing that should provide the clearance necessary?

[Matchless?58]

Thanks gecko . I had a look at the engine diagram and there is no spacer fitted . The thermostat just sits on top of the housing and is held in place by the top half of the housing which bolts down onto it . I had a look at your link and the thermostat I got from vicary plant is the same ( although cheaper ) so all good there . It won't fit in the space and I'm fairly sure that old bit of hose is not an OEM part so I will go for it and pull it out . I'm going to have a look today if this rain actually stops for a while . I will update later .
Cheers Chris

[Matchless?58]

Hi Just an update if anyone is interested . I had a go at the machine today in-between rain showers . I pulled out the suspected bodge and have posted a picture . I don't think this was a genuine JCB part ! Someone obviously was to tight or couldn't be bothered to replace the thermostat properly so did a quick bodge . Just for future reference the thermostat sits in a nice neat little rebate in the top of the housing and the hose coupling part bolts over it to hold it in place . This all became clear after I removed the bodge . I used a fine smear of 3 bond sealant each side of the gasket to make sure of a complete seal . I didn't have time to run the machine up as it was getting dark and I had other stuff to do . Work tomorrow so won't be able to test until Wednesday . Thanks everyone for your input .

[Jeremy Rowland]

Wow that is some bodge; now you have taken the bits out you can see what they are, and they most certainly don't look to be standard to me. Don't forget that when you do run the machine up, when the new thermostat opens the coolant level may drop so you may have to top it up, not always the case but always double check.

Jeremy