300 tdi too hot?

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Originally Posted by Trout

Yep think so. I have a low water alarm and even a slight drop in water level sets it off. Having said that I have read Blacknights method a few times now and don't quite understand how it works.

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first off, check the vactuator valve,

The coke bottle bleed works by providing a higher head of water that can exchange for whats in the expansion tank and providing a visual indicator of what the coolant is doing.

BUT if the vactuator valve is knackered you can still wind up with an airlocking system that will look to be bled right but the radiator is not full, when you crank it up you areate the coolant (at best) reducing its effeciency.

but at this point my money is on your VC and shrouding being the first part of an airflow issue combined with a thermostat thats not opening correctly, and I dont care if its new. I've run out of fingers and toes to count the number of them I've had faulty from new.

Also when was the last time you had the radiator and cooling system flushed out and backwashed?

Thanks Dave. Radiator core is new and shrouds are all place. vactuator is not blocked - at least I can blow and suck through it.

Got a IR temp gauge tonite and went for a blast. Started from cold and we have moderate hill about a km from home. At full throttle i can hold 5th at about 90. Hill is a few hundred meters long. By the time I hit the top temps by the gauge were over 100. It’s warm tonite and aircon was going. Temps drop off to about 95 by the time I can pull up after a short downhill run. Highest temp i could pickup with the I.R gauge is about 90 when reading up close to the sender in the thermo housing. Head varies but not more than about 90. Radiator top about 85 and about 60 odd at the bottom.

Could not stop the viscous fan with a paint brush...well the soft end anyway 😀

So maybe the VDO gauge is reading high? Will drive it a bit more tommow when it is hot and do a few more measurements.. will try a the coke bottle fill but really don’t want to drain all my coolant again! I assume topping it with the coke bottle method will work just to bleed.

Quote:

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Originally Posted by Trout

Thanks Dave. Radiator core is new and shrouds are all place. vactuator is not blocked - at least I can blow and suck through it.

Got a IR temp gauge tonite and went for a blast. Started from cold and we have moderate hill about a km from home. At full throttle i can hold 5th at about 90. Hill is a few hundred meters long. By the time I hit the top temps by the gauge were over 100. It’s warm tonite and aircon was going. Temps drop off to about 95 by the time I can pull up after a short downhill run. Highest temp i could pickup with the I.R gauge is about 90 when reading up close to the sender in the thermo housing. Head varies but not more than about 90. Radiator top about 85 and about 60 odd at the bottom.

Could not stop the viscous fan with a paint brush...well the soft end anyway 😀

So maybe the VDO gauge is reading high? Will drive it a bit more tommow when it is hot and do a few more measurements.. will try a the coke bottle fill but really don’t want to drain all my coolant again! I assume topping it with the coke bottle method will work just to bleed.

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first up have you done the gauge calibration?
Second have you got the IR themometer calibrated? (Mine is set up for Matt black paint I always paint a bit on when I need to be accurate)

your cold calibration is easy, ignition on in the middle of the day and read the sender with the IR thermometer. if those numbers are the same onto the next step.

get a pot, paint the side black (same as the paint you used on the thermostat housing) and keep it off the flame boil the pot full of water turn the flame off and IR the paint. you should have 100 Deg C (adjust for atmospheric pressure if you want to hit the .1 degree accuracy)

now start the car up and with the radiator blanketed (or the VC removed, let it idle up to temp as you watch both the guage and the IR.

Dont forget to read the temp on the outlet hose, heater hose and inlet hose. you should see some funny number shimmy as the thermostat tries to balance the temp.

IT might also be worth checking to see which way round you have the thermostat, i've seen one installed the wrong way (after market item) and many with the hole in the wrong spot or blocked up.

Thanks Dave. No to the calibration. I did try the IR on some boiling water and it was reading 98.xx

More homework for me tomorrow. I know about the correct thermostat orientation so pretty sure it will be right. Can I pull the guts out or leave it out altogether as a test.

Rod

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Originally Posted by Trout

Thanks Dave. No to the calibration. I did try the IR on some boiling water and it was reading 98.xx

More homework for me tomorrow. I know about the correct thermostat orientation so pretty sure it will be right. Can I pull the guts out or leave it out altogether as a test.

Rod

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yep

Try locking the VC on the fan - hardly any noise increase , and remove any roofrack (worked for us)

When you went to vdo temp gauge, did you change to the appropriate sender ? I have both a low water alarm which works on water level and one that works on head temp. when you put in vdo did you use the old wiring. May be worth running some fresh ones especially earth. I went up to the cape earlier this year towing a camper. Temp on vdo showed 95 consistently and head temp maxed out at 85. (1998 130 4 door)

Also make sure the capillary tube from the sender to the gauge is not kinked and is running at its most flat alignment. ie not going up and down or around tight corners. Will help with coolant flow to gauge. Also may be worth running the capillary tube in a protective/heat resistant covering/tube.

I've still got my money on viscous fan and/or thermostat not operating properly. I had the exact same temp spikes recently with the previous thermostat and VC being less then 12 months old. The old VC had good resistance, but clearly at speed (which would be hard to test with a paint brush whilst driving at 100km/h) the VC was not working properly.

I'd try replacing these first. Then it will be a process of elimination.

I am going to be adding these as 12 monthly maintenance items from now on.

Just a thought you said you have a bigger intercooler. Has the injector pump been played with ? Do you have an egt gauge? More fuel more heat ?

Thanks everyone for helpful posts. VDO gauge is electrical and sender was supplied by Otto instruments. Original wiring. Yes it has has pump tweaked and turner head which give a bit more power so expect a bit more heat. Tune is very modest though. No egt gauge ...yet.

Did blknights I.R calibration and black paint suggestions and I am now confident both the VDO gauge and I.R. Thermometer are reading reading fair.

Did coke bottle bleed and went for test drive this morning up my usual hill. Ambient temp 32oC Started with car warm and pushed it flat out for a bit. Temp peaked just below 100. Not Running as hot as last night so maybe bleed helped. But I am not convinced it has solved the problem.

I think this is a clue though. Pulled up with temp gauge showing just under 95.

With IR.guage head was 90-105. Sender 96. Top radiator hose 78. The little thermostat bypass hose 95-90. Heater hoses 87-88. Radiator bottom 59. Radiator top 80s.

So what do you think? Thermostat faulty I reckon even though it’s new. I replaced it when I did the head. I checked the temps from cold when doing bleed and it looked like it was not opening. Even when sender was in low 90s. Top heater hose was only getting low 80s.

I guess it could still be water pump not circulating properly. I have ordered a new water pump anyway but will pull the thermostat out for a test run. More coolant on the floor again 🤨.