Coolant temp a steady 105 Deg?

[laketahoequattro]

Yes, water came out, but not at the velocity I would expect now looking back a few days ago when I flushed the radiator.

It is not uncommon, the car had old coolant in it when I bought it and did trans swap. I replaced the pump 300miles ago so it is brand new and I figure the car would completely overheat if that was broken.

Not sure what else could be causing the symptoms I am describing.

[David's8]

Is it looking like the pump itself? Some of the non_OEM pumps used (as replacements) had plastic impellers which were subject to breaking up. It might be that thats the cause?

[laketahoequattro]

I replaced Hepu brand metal impeller water pump. If it were bad I would imagine the car would overheat instantly. After looking at some radiator flush videos on youtube, my radiator did not flow water out of the bottom pipe as fast as I think it is supposed to. Im going to try replacing it and do a heater core flush as well. Joys

[Mechcanico Lee]

Good test for waterpump impellar....... take car for a run put heating up to full put blower up to full , if the heat stays hot all the time the impeller is spinning well , the heater is the furthest item away from the waterpump , if the heat stays good the water pump is good , i have on various cars when the water pump starts to spin on the plastic impeller the heater will start to go luke warm ......in some cases it will go cold and you see a pretty instant rise in the temp gauge as you have still water in the block .

Does sound like a partially blocked radiator , the silt will tend to block ther lower vanes in they are horzontal vanes , if they are vertical vanes it starts to clog the lower areas ....... Shoguns tend to suffer with this issues , you can try to flush the rad but in my experience it just doesnt work , the water will always take the easyiest path and flow down the vanes that are good .

Also with chemical flushes you have to watch that the silt does not end up in the heater core vanes as a consequence , then you have an epic task of replacing the heater matrix core .
Lee

[laketahoequattro]

After replacing the thermostat last week, I tried to get my cabin heat to function well again as it is freezing outside now and no dice. I bled the heck out of the top screws, but I am getting 3/10 heat in the cabin. Top heater core pipes are both hot. I am now starting to lean towards an issue with the aux water pump as well. I am going to test that next to see if the solenoids are clicking and the outlet pipes are hot. The fuses are good. Oh joys

If my water pump was bad, the car would overheat instantly correct? I have seen blown out water pumps on 1.8t's and 2.7t's and they overheat as soon as I drive 100 yards.

I greatly appreciate your input. Much thanks!

[ainarssems]

It's unlikely to be pump if it was new pump with metal impeller but still a possibility, maybe it was not exactly the same and there is too much gap between impeller and casing so it just stirs coolant but does not pump around much or it could be loose belt slipping on pump pulley and not turning it at full speed.

[David's8]

It seems such a simple system and should be easy to diagnose faults.

I just had a look at the service manual (again) - I read the cooling section section avidly a few months back when I had an overheating issue) and it states that the 'stat starts to open at 87degC and should be fully open at approx.102degC - but that there's no way to test that. I know from monitoring my own system using VCDS that the electric fan cuts in around 97degC. I did find however that the VCDS temp was frequently around 105 when the gauge on the dash showed it steady at 95ish. However, since the 'stat replacement I havent tested the system using VCDS sensor derived data against the displayed temp (I have too many other things to do!) and as the display shows a rock steady 95 i have been content to leave it like that.

[Mechcanico Lee]

Im getting a little lost on the diag .....i thought the heater inside was good but you say there not very good now, after a run is the top radiator hose hot and the bottom one slightly less hot .

If the bottom one is still cold or cool thats more like a thermostat not opening ......i have seen this with new stats even genuine ones , sometimes the engine gets really hot before it opens but after that there ok .

Take it for a run around the local roads then test hoses , it could still be trapped air , when the stat opens the header tank will empty because of the space the air has taken .... also did the new stat have the 'giggle valve' .....no im not taking the micky , its the little valve thing that blocks off a small hole is the stat housing , its that that allows the air to bleed through as you fill the system with water ...some non gen stats dont have it , but when the stat opens the air will burp up to the top anyhow .

The heater thing could be related to air in the system but you say the water was bleeding out of the bleed screws , even with the auxillary water pump not working i would of thought the engines water pump would of been more than capable of pushing the water through past the aux impeller .

Need to go one step at a time, get the radiator flowing first so both hoses are hot if the water pump is pumping in air space or partial air space its ability to pump will be greatly reduced .

Lee

[laketahoequattro]

Originally Posted by Mechcanico Lee

Im getting a little lost on the diag .....i thought the heater inside was good but you say there not very good now, after a run is the top radiator hose hot and the bottom one slightly less hot .
Lee

Yes originally the heat was a 6/10 before I swapped out the t-stat. Now it is a 3/10 when driving and 0/10 when stopped. No lower rad hose is ice cold, top is very hot.

Originally Posted by Mechcanico Lee

If the bottom one is still cold or cool thats more like a thermostat not opening ......i have seen this with new stats even genuine ones , sometimes the engine gets really hot before it opens but after that there ok .
Lee

I tested both old and new thermostats in boiling water and they both opened at the correct temp.

Originally Posted by Mechcanico Lee

Take it for a run around the local roads then test hoses , it could still be trapped air , when the stat opens the header tank will empty because of the space the air has taken .... also did the new stat have the 'giggle valve' .....no im not taking the micky , its the little valve thing that blocks off a small hole is the stat housing , its that that allows the air to bleed through as you fill the system with water ...some non gen stats dont have it , but when the stat opens the air will burp up to the top anyhow .
Lee

Yes both stats have the ball vent hole that I installed at 12 oclock. I did drive it around and made vcds show 106 degrees, but lower hose is still ice cold.

Originally Posted by Mechcanico Lee

The heater thing could be related to air in the system but you say the water was bleeding out of the bleed screws , even with the auxillary water pump not working i would of thought the engines water pump would of been more than capable of pushing the water through past the aux impeller .
Lee

Yes I am getting water to bleed out of the screws, no more air. I tried bleeding with car flat, at an incline, and facing down a hill. Just water. I will be testing the aux tonight.

Originally Posted by Mechcanico Lee

Need to go one step at a time, get the radiator flowing first so both hoses are hot if the water pump is pumping in air space or partial air space its ability to pump will be greatly reduced .
Lee

Yep this is my next step. I found a radiator for 200 USD shipped and tested w/ warranty. This is what I think is happening too, that there may be an air bubble down by the water pump impeller, Just don't see how this is possible. I sure hope the radiator fixes the over temp issue.

Is there a way to bleed the system more towards the aux heater also?

[Mechcanico Lee]

Don't worry about the heater yet , the radiator is the priority unless it is majorly blocked you should have flow, even if some of the lower vanes are blocked the water will flow up the side cores .
What you may have to go is leave the t stat out , sometimes you have to cut the Center out because the sealing ring is on the outer circumference .

If you have a new water pump in there with a steel impeller I'm sure that will be ok , in fact the point you say it doesn't overheat badly tells me it is flowing water albeit in a closed block situation

With the stat left out run it up , in theory it should not get up to temp very well , revving up stationary it will get warm but on the road it should over cool , you are doing this as a diagnostic test ..... if the bottom hose is still cold then yes it's symptoms of a blocked radiator .

If you get it all bleed up and working stationary and then go on the road and the temp drops right off this proves somewhat that the radiator is good

Have you seen the temp gauge go right over to overheat at all when the t stat is in , the vcds reading may be at took from near cylinder heads which is the hottest area of the water , where is the t stat on the engine is it on top hose or is it lower down in engine block in a cooler area .

Does the top hose get so hot you can't even touch it ? I have had cars especially ones that have stood for sometime where it goes into the red on the temp gauge before the stat gives up and opens , you know when they get really hot because the hoses start to 'thunk ' or it starts to spill out of the header tank badly .

Just another thought is there any smaller bore pipes that come off the top of the rad that go back to the header tank , the smaller bore pipes are more prone to a blockage and its these pipes that aid the bleeding action as you fill the engine with water
Keep at it ,one step at a time .... carry out tests , rule out , carry on

Lee