Thermostat? Overheating issue

Ok guys here is the short version

1. Car overheats on the highway, I pull over and see that it's gushing out coolant out of the hose that goes from the block to the oil filter top.
2. Hose is replaced.
3. 20 km from home on the highway this morning the temp goes up again, I pull over and see that coolant is coming out of the coolant resevoir, or around that area.

Think it's my thermostat? Where is it located ? Car is a 95 1.9 TD...thanks guys!

Anybody? I have it at a local VW shop, but I don't want to get screwed over...seems I already am! Anyways, car is overheating under load, when I have it going 100km an hour it over heats after about 5 min....anyone???

No body to help a chicky out?

Is the water pump pumping? I think the impeller can slip of pumps with plastic impellers.

Check the thermostat to make sure it opens. Put it in a pan of water heated to a couple of degrees over its opening temp (or just replace it w/ a new one). If you remove it, it will be a good time to change your coolant, because you loose most of it when you remove the T-stat. Its most inconviently located in the lower coolant hose flange (on the waterpump housing). There is no drain petcock on these cars.

These cars tend to run hot when under an extended load anyway.

--Nate

On my car (92 Passat TD, engine code AAZ) the thermostat is located inside the flange attached to the engine block from the lower radiator hose. It is somewhat of a pain to change because the power steering pump must be removed to access it. The power steering high pressure line ($260!) is easily damaged! Ask me how I know.

I don't know if that will help you out at all.... good luck!

Normally when the car is overheating under load as described the plastic impeller on the water pump has given up the ghost. You can turn on the heater and fan full to help increase the cooling for a short time - basically to get you home.

However my own car was overheating in a similiar fashion, but following replacement of the water pump and thermostat it is still overheating under load. In addition, there is no water in the oil, which should hopefully highlight that the head gasket is intact - so in my case the next check is all the coolant hoses and the radiator.

Well guys, my head was done. I had it replaced and it's still overheating. Randomly once it will overheating just crusing at 100km/h, then will be fine in 20km traffic, and vice versa. No coolant is leaking. And it's not coming out of the overflow now...it was before.

SO basically I'm thinking something cause the hose to burst, then overheat and then cause my head to go...but what? There must be something clogged!

There have been reports of failed whater pumps where the plastic impeller will be loose on its shaft and sometimes not pump coolant. Its best to get a metal impeller replacement.

3-5 possible causes , leaking under pressure hose , blown head gasket or warped & cracked head , or a failing water pump or sticking closed thermostat . Or you could have a clogged up radiator .

rotarykid said:

3-5 possible causes , leaking under pressure hose , blown head gasket or warped & cracked head , or a failing water pump or sticking closed thermostat . Or you could have a clogged up radiator .

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Head gasket and head where just put on, new gasket and head that was minty. Thermo was new, and as for the water pump...new as of 1.5 years ago. I'm thinking the rad. I heard about something you can buy to flush the rad, some type of chemical...anyone?

Only one way I know to fix a clogged up radiator . Remove the tanks and rod it , that is run a rod through the cooling tubes to remove any clog .

Have you verified that there isn't trash & leaves in between the radiator & condensor coil blocking the air flow ?? This is a common issue on cars your age .

rotarykid said:

Only one way I know to fix a clogged up radiator . Remove the tanks and rod it , that is run a rod through the cooling tubes to remove any clog .

Have you verified that there isn't trash & leaves in between the radiator & condensor coil blocking the air flow ?? This is a common issue on cars your age .

Click to expand...

I will look and see about the garbage. If the water isn't going through the rad though, wouldn't the rest be coming out of the overflow? As in back pressure?

Did that so-called new waterpump have a plastic or metal impeller? If plastic, then I would be more suspect.

weedeater said:

Did that so-called new waterpump have a plastic or metal impeller? If plastic, then I would be more suspect.

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I don't know/remember. Is there a way to check if the water pump is working? What about hoses that are cold...I asume that if a hose is cold then coolant isn't getting to there...right? Sorry for the newb questions, but a girl has to start somewhere

mk3_gurl said:

I will look and see about the garbage. If the water isn't going through the rad though, wouldn't the rest be coming out of the overflow? As in back pressure?

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No , not necessarily . If you have as little as 10-20 % of the tubes clogged water or air tubes this will restrict flow causing the engine to overheat .

VW cooling systems commonly operate @ pressures and in a heat ranges that don't allow for a little or any reduction of cooling and still funtion adiquately . A small block in either air or cooling fluid flow often times leads to an overheat which can cause cooling system damage which often leads to more overheating issues .

Gottcha. Any other things to check? Some people are saying it could be a bad/warped head that was sold to me In that case I'm selling her

mk3_gurl said:

Gottcha. Any other things to check? Some people are saying it could be a bad/warped head that was sold to me In that case I'm selling her

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Anyhing is possible , I surely would hope not though .

Can anyone give me a list of things to check from easiest to hardest?

What year is this car? What engine?

Is it a mk3 as your screen name suggests?

If so the plastic impeller theory is pretty much null and void, that really only applies to mk4's. I've never seen the old fiber impellers fail on pre mk4.

Is the bottom hose from the water pump to the radiator getting hot? If so then your thermostat is working.

Is your thermoswitch / electric radiator fan working when the engine is up to temp?? If not and your bottom hose is hot that might suggest a plugged radiator.

What color is the coolant? is it possible that someone mixed the pink and green coolants when they did your water pump last year? Mixing of coolants causes solidification.

If the head was warped again, you would likely see air bubbles percolating up into the coolant bottle, it would also likely run badly.

I hope when it starts getting hot you are shutting it down right away, it doesnt take but a minute of drivin g it hot to warp a head. You don't continue driving after you see the guage rise right?

If it turns out to be the radiator, buying a new one is a better option that messing with trying to clean an old one out. Radiators are really cheap for older models, less than a hundred bucks for most.

Start with easiest thing, the stat. Remove old one and put
into pot of cold water and bring to a boil. Note at what temp., it just starts to opens. Also good idea to test the brand new stat this way too. Make sure you get the wright stat, for a TDI's are diff., then other VW"s, so the service manual says.

BTW - We still have no clue what platform car we're dealing with here...

Everything 4 cyl (ABA,AHU,1Z,etc) 1975 - 1998.5 uses essentially the same t-stat..