Quality thermostat

[edddo]

Having watched the engine temp on the TM4 for a while I am convinced that my thermostat is faulty as it takes too long to get up to operating temp of around 82 C - 25 km at hwy speed or 20+ minutes around town on a warm day.

What is the best brand of thermostat for my D1 diesel? Dont want to put anything dodgy in.

thanks

[rick130]

Waxstat is the OE brand and the opening temp is up around 87*C, but....

if your car isn't getting warm, it may be the oil t/stat jammed open too.

Pull your water t/stat and test the opening temp, (pot of water, t/stat suspended by some wire and a digi thermometer)
If it tests ok your engine oil t/stat is jammed open.

[edddo]

thks Rick
Didnt know there was an oil thermostat!

[rick130]

thks Rick
Didnt know there was an oil thermostat!

Yep, oil t/stat is behind the oil union and two bolt flange pointing towards the chassis rail above the oil filter.

[edddo]

Ready to put the new Waxstat thermostat in. Is there a recommended way to avoid letting air into the cooling system when I do this- I Know the 300tdi can be prone to airlocks in the system?

thks

[edddo]

Ready to put the new Waxstat thermostat in. Is there a recommended way to avoid letting air into the cooling system when I do this- I Know the 300tdi can be prone to airlocks in the system?

thks
bump

[bee utey]

bump
The 8mm bleed hose connected to the thermostat housing and running under the a/c pump, should clear any air all by itself. Make sure it isn't blocked at the black plastic tee fitting near the radiator. It is a jet pump that acts to remove bubbles from the engine and the top of the rad and convey them to the expansion tank. If working properly you need to do nothing other than check the tank level after running the engine at fast idle for a few minutes.

[edddo]

ok so I took out the old thermostat, siphoned maybe half a litre out of the housing so as not to spill it, refitted the new one, reassembled, topped it up at the filler on the thermostat housing. Let it odle for a while, level in tank looked good and took it for a drive. about 10 km up the road the coolant alarm went off. Pulled over, let a bit of air out of the DS radiator ( where the coolant alarm sensor is) via the 8mm hose there - it self bled and off I went. Repeat this 3 times and now Im home.

So

How do I bleed the cooling system properly now that I have cleverly let lots of air in?

Need car tomorrow so any help appreciated

thanks

edit: did a search and found a how to thread..so ok

Lindsay

[ade]

should be self bleeding, i havent ever had a problem when replacing cooling components, make sure the heater is on when trying to bleed the system

[edddo]

The 8mm bleed hose connected to the thermostat housing and running under the a/c pump, should clear any air all by itself. Make sure it isn't blocked at the black plastic tee fitting near the radiator. It is a jet pump that acts to remove bubbles from the engine and the top of the rad and convey them to the expansion tank. If working properly you need to do nothing other than check the tank level after running the engine at fast idle for a few minutes.

Some time ago I replaced the original black plastic tee with a brass tee. From what you are saying, the replacement part does not replicate the original. Perhaps this is why I had problems today?

[bee utey]

Some time ago I replaced the original black plastic tee with a brass tee. From what you are saying, the replacement part does not replicate the original. Perhaps this is why I had problems today?
Yup. The black plastic thingy has a restrictor jet in the hose from the thermostat. If your brass tee is arranged so the straight through flow is directed to the expansion tank, it has some minor suction effect on the rad air bubble. You could modify the tee with a small copper tube in the inlet side to replicate the OEM plastic thingy, although it sounds like you've finished the bleeding already. After the engine and heater are bled automatically of air, the only other place for air to collect is the radiator. Bleed it off any way you like and you're safe until next time you work on the cooling system.

[stumps]

Linds, My t'stat also takes a quite a few k's/mins before it opens up. and is a relatively new item...pot bench tested etc.
I reckon that with the bypass purge line the engine is effectively continually mixing quite a stream of 'warm block' coolant with 'cold' coolant downstream of the t'stat (radiator, exp tank, hose etc), which may explain the time taken amongst other items as discussed.

I am a bit paranoid about the purge line becoming blocked (as it was when I purchased my Disco) so every so often shine a LED lamp on the side of the expansion tank (clear type) and can easily see a surprisingly strong flow that comes from the bleed outlet on the t'stat housing....this flow also sucking in cooler radiator fluid.

ps. when I bleed mine if I have pulled hoses off everywhere etc, I unscrew the expansion tank mounts and carefully raise it above the engine and heater hoses etc as someone here had done (sling it with some string from the bonnet catch), then add from there, thus highest point in the system and some good head to purge through to t'stat bleed. But if your purge line is the factory piece (with venturi) and working well, probably just the service manual way is good enough.

[edddo]

Thks for the replies.

Well I bled mine by simply topping up at the thermostat until the expansion tank was full then putting the lid on and continuing topping up until the thermostat housing was full. Then run until warm and let it cool down (overnight)and then top up again at thermostat housing. Repeat until thermostat housing stays full. Then I siphoned some out of the expansion tank( to just above seam) and it has been ok.

I found the old plastic tee piece - but it does look flimsy ( and is now about 15 years old-and have been known to break IIRC) to me so not going to use it.

The old thermostat I took out was a Waxstat with a 78 degree stamp on it. Apparently the one I put is is rated at 88. Indeed I am seeing higher temps on the TM4 now - up to 92 today 35degrees, 110 with aircon on. It doesnt get up to temp much, if any, quicker than the old one though - so maybe that is just how D1's operate, or the oil thermostat is stuffed as mentioned earlier in this thread?