Cooling system troubleshooting TD27

[cowman]

Hi guys,

92 terrano td27

Replaced water pump (almost no fins left on impeller, heater wasn't going, can't have been pumping water) was leaking for a while so it just had water running thru the system.

Everything quite rusty. Flushed out radiator with garden hose, new radiator hoses.

Replaced thermostat.

New radiator cap

New drive belts.

New coolant.

No leaks, runs ok until a hill then temp gets right up to 3/4s, top hose hot bottom hose warm however far cooler than top hose.

Can't see coolant moving thru radiator either hot or cold?

so is the radiator blocked or have I not installed thermostat correctly? The only thing I can think of is that i used rtv silicone on the thermostat housing and it may have creeped in when clamped down? Does the big flat disk move or just the spring loaded part on the inside?

Should I be able to see coolant flowing? And noob question here but what direction should it flow, top to bottom or bottom to top?

[cowman]

Might be answering my own question here but if the thermostat had opened like it should then it would make sense that the top hose is hot?

And bottome hose cool because it has cooled down before it goes back into the engine? But if it's too cool then waters not actually getting thru, either not being pumped or flow is restricted to much?

New radiator or a professional clean?

[BlakeNZ]

Coolant always flows top to bottom, which is why the top of radiator(and top hose) is always hotter than the lower hose.
I would pick that the radiator is partially blocked up with crud, and needs to be "rodded", whereby they remove the end tanks and clean out the core properly.
did you use sealant rather than the thin termostat (paper type) gasket?
I doubt you installed the thermostat incorrectly, or that the excess sealant has blocked it.
The big shiny stainless disc stays still, and a hole opens up in the centre of that disc when the heat causes that spring to move slightly.

[cowman]

Sealant aswell as gasket, that's good I don't think that's the problem then, must be just when it's really working and hot there's not enough flow thru the radiator ? Any other way to make sure that it is pumping?

[stovanovich]

are you judging the 3/4 temp off the standard gauge? If so then perhaps look into investing in an aftermarket gauge as that standard one is a tad iffy. I run both the standard & an aftermarket one which gives me much clearer idea on the temps (accompanied by an EGT too of course)

[cowman]

Yes standard gauge, aftermarket one with that shows actual temps? I.e degrees c? Are they all the same?

[oljamesyboy]

have had the same issue with mine so put after market gauge in it and from just under half to 3/4 on factory gauge is only 15ish degrees on after market one.
i have pushed mine hard on up hills and has never gone over 3/4 on factory gauge (about 100-115 on after market one)

[zed]

Drain everything out of your cooling system. Go to pak n save buy a 1kg box of soda crystals. Mix whole box of crystals with hot water. Fill cooling system from mixed water and rest to top up. Turn heater on hot let it run until thermostat opens, top up anymore that needs to then drive it for a day or two. Will get most of the stuff out. You may need to drop bottom rad hose if lots of crap as may block the tap. Once drained run a cycle of straight water through (ie get it hot etc) before refilling using coolant. Btw "Pure Dew" from red shed (10L for $7) is the best de-mineralised water for radiators and batteries available.

What that process doesnt remove will only be possible via mechanical means (ie rodding as BlakeNZ said) or replacement.

2c

Edit: make sure if you still run an aircon rad in front of water rad that it isnt blocked with mud...mine was caused some overheating until I removed water rad to clean aircon. Also pay to check your viscous fan...although iirc nissos are part of the water pump?

[cowman]

So after getting it hot again (3/4 temp) I checked the fan- it was no harder to move than when cold. This is with a brand new water pump and viscous hub attached, what should I do??