Outer Limits 4x4 Board

I've just replaced my water pump because it was leaking and giving me overheating problems. I put everything back together and started it up to bleed the cooling system and after 10mins of running the engine is at operating temp and is hot on the top. I felt the bottom of the radiator and it was cold as a stone.

Question is......does this mean I've got a blocked radiator? The radiator is a bit on the suss side but it doesn't appear to be leaking anywhere. After running it for 15mins it still wasn't warm at all on the bottom. I had the radiator cap off so i could monitor the coolant level. Motor is a 2H in a 47 series cruiser.

First of all pull the thermostat out boil some water and put it into a container with the thermostat if it opens it's ok if it stays shut thats whats stopping flow chances are this is whats wrong they don't cost all that much and could have been a major contributor to the overheating in the first place

Yeah I got a new thermostat when I got the water pump. Figured I may as well change it too.

so it's been fitted and it still doesn't flow or haven't you done it yet

I've fitted the thermostat and water pump. I only ran the vehicle for 10-15 mins at about 1200rpm

It'd be very blocked to make it stay totaly cold possably it was at run temp but not enough for it to open Best way to see if radiator is blocked undo the hoses off the engine end put the hose in the bottom hose and see if it builds pressure and doesn't come out the other end or if it flows if it only flows a little put it in the top and back flush it but if thats the drama and you think it's sus maybe it's time to shell out for a new one Keep me posted

Always test the thermostat before installin git. We find at least 30-40% of aftermarket thermostats wont open out of the box

Thats bullsh*t. You think they would have better quality controls

I agree!

Some will open part way and refuse to open any further, others will not open at all. The rest work as they should

Most of the time we use genuine if possible, but always test them first. much higher success rate!

Will take you 5 mins to put him in a pot of water, well worth the time when it can cause your engine to overheat

Go through the motions of boiling the new thermostat to see if it opens. I put a new one in when I installed a new radiation a few years back and it ran hotter, so ended up putting the old thermostat back in.

If you are concerned about the radiator being blocked, put some flush cleaner through it. BUT before doing it, get an old stocking from the missus, and put it in the TOP radiator hose so it catches all the crap that dislodges. feed it in the pipe (you only need about a foot of it) and then wrap the outside around the pipe to hold it firmly in place.

Put your cleaner/flush in, and CONSTANTLY MONITOR the temperature guage. If there is heaps of crap in there the stocking will fill up with it and can block the flow of water. If needed, you can let it cool down, empty the stocking and do it again.

This also stops large lumps of debris/scale breaking away from inside the engine and clogging up the radiator.