92 jetta 1.6 na overheating

[nissannx]

Car started over heating on highway only. Would always stay under half for the past 3 months. Now it goes past 250f. Half the rad is cold. The side that controls the fan is cold.

I tried searching online but people never reported on how they solved the problem. It cools back down at idle.

I'm going to take everything apart and flush it on Sunday. I will test my thermostat as well.

Any online write ups on how to remove the thermostat? I have power steering.

Anything else I should be looking for?

Thanks

[vanbcguy]

The power steering pump has to be unbolted to get at the thermostat housing.  You don't have to unhook the power steering lines, but the bracket that holds the power steering pump on needs to be removed (but the pump can stay attached to the bracket)

It's enough of a pain that I'd just buy a new thermostat and some fresh coolant.  There is no drain anywhere on the cooling system, when you open it up you'll have a gusher of coolant that runs over all sorts of grimy engine parts making it not suitable for reuse.

Also make sure your thermostat comes with a new o-ring.  Plus you ABSOLUTELY should replace the thermostat housing - it is made of plastic and rarely will seal well if removed and reinstalled.  They are CHEAP, like under $10.  It's a huge pain to have to get back in there again to deal with a leak.  If your car has the two-piece coupler joining the lower rad hose to the thermostat housing it would be wise to replace that too.  There's another o-ring that needs to be replaced as well if you have that bit.  If the rad hose is connected directly to the thermostat housing then you don't have to worry about that part.

http://www.partsbase.org/vw/jetta-jem-us-1992-12100-coolant-pump/

[nissannx]

Driving home wasn't good.  Had to pull over 3 times.

Rad is ice cold but the rad hoses are hot. Does this sound like a failed thermostat? Would it stop coolant flow to the rad?

[TylerDurden]

Yup.

Maybe a bad WP.

[TylerDurden]

Does this car have the goofy split pulley on the WP?

[nissannx]

The water pump has a groove for a belt to the crank and a groove for the alternator to the crank

[TylerDurden]

I usually see the later WP pulley with the sheave that drives the PS pump... That split pulley will not drive the WP if the PS belt is off, since the alternator sheave is designed to run like an idler pulley.

[air-cooled or diesel]

the p/s pulley on water pump also goes 1 way; with a/c and w-o a/c.

[nissannx]

The power steering belt is on and the power steering works. The belt is tight for the water pump

[TylerDurden]

Another possibility is the impeller for the WP has come loose. When the t-stat is out, a screwdriver can be used to check if the impeller is still tight on the shaft - try turning the pulley while blocking the impeller with the screwdriver.

[TylerDurden]

I prefer to extract as much coolant out of the system by siphoning from the reservoir tank before opening the lower hose. Low pressure compressed air into the bleeder hose makes more coolant rise into the tank.

Another trick is to shove a thin screwdriver into the lower hose along the t-stat housing (after removing the clamp), to guide coolant away from the dirty parts.

Both of the above methods are slower than just pulling the lower hose, but they help keep the floor tidy and reduce loss.

[fatmobile]

 How does the flow into the coolant resevoir look?
 It's common for the restrictor in the small hose to clog and air gets trapped in the block.
 Easy fix for a common problem.

[nissannx]

It wasn't moving then in 5 minutes just started coming out the reservoir.

[air-cooled or diesel]

if you mean the water wasnt flowing @reservoir tank; a blown water pump can do this; that means you have to drop the thermostat housing and see if impeller is just spinning. you need a new thermo, oring, coolant, and various other things help out.
if by coming out of tank thats it boiling in your block, ummm, i hope you dont plan to do that too much,,

[nissannx]

I just ordered everything today. New housing oring and thermostat. Will check the pump once I'm inside.