ZD30 Overheating (I think)

[rusty_nail]

Hi Guys,

I just installed a new factory dash temp sender as my old one was jumping all over the shop. took it for a drive this morning and after about 20 mins of driving(mostly downhill) the gauge started warming up. i made it home and let it sit for a few hours, checked levels, plenty of water/coolant in there so took it for another spin to see if it would get hot again. i got less than 2 ks from home and it started getting very hot. took it home, pulled out the radiator, flushed it, reinstalled and put in some brand new coolant. took it for the same drive again and its still getting hot.

just looking for advice on what the next step would be? i checked my invoice from my motor repair in 2015 when it was fully rebuilt, it had a brand new water pump and thermostat installed then? is there any electricals that relate the the motor cooling that i should be checking? or should i be looking to replace the radiator?

any help would be greatly appreciated

cheers

Rusty

[PeeBee]

I have a radiator pressure test kit if you want to pressure test the system - is it actually leaking or consuming water? Could be the thermostat - thats another starting point.

[MB]

G’day Nicko mate, check the engine fan is fully or near locked up when it’s hot and turned off. Viscous coupling could be failing possibly?


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[PeeBee]

G’day Nicko mate, check the engine fan is fully or near locked up when it’s hot and turned off. Viscous coupling could be failing possibly?


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How could i possibly forget that one!!!

[MB]

Too many Wheat beers for YOU possibly, all the above may or may not be his answer needed? Worth a quick check though, hopefully a simple fix, Happy Days ;-)


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[rusty_nail]

G’day Nicko mate, check the engine fan is fully or near locked up when it’s hot and turned off. Viscous coupling could be failing possibly?


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thats definitely turning mate

[rusty_nail]

I have a radiator pressure test kit if you want to pressure test the system - is it actually leaking or consuming water? Could be the thermostat - thats another starting point.

not consuming water, and no bubbles coming outta the radiator, i dont think its motor related, the motor is only 3 years old and has done less than 20 thou. i hope its not thermostat thats only 3 years old and its in a prick of a spot to get to lol

[Hodge]

Hey Nic. Since you installed a " new" temp sender, could that actually be faulty or not wired right maybe ???
Just brainstorming.

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[MB]

Do you mean it’s turning when car is hot and turned off and or turning when running mate?
Only reason I genuinely ask is that Growler & Rainsey here & many others all experienced not fully locking up when hot needed they found.


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[rusty_nail]

Hey Nic. Since you installed a " new" temp sender, could that actually be faulty or not wired right maybe ???
Just brainstorming.

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could be a possibility, i bought it from atoc(on here) its a genuine temp sender, and all i did was unbolt the old one and plug in the new one.

[Hodge]

could be a possibility, i bought it from atoc(on here) its a genuine temp sender, and all i did was unbolt the old one and plug in the new one.

Only reason I mentioned it was I went through the same thing. Mechanics cracked my factory sender when they were doing other work.
They fitted a new sender, and for the next week or so, every now and then the temp gauge just sky rockets... Long story short. It was a brand new sender that was DOA.
Do you have a infra red thermometer by any chance?? Thats how I ended up finding out my sender was faulty. I was aiming the infra red at the thermostat and whether the temp gauge was on half or all the way up, the temp at the thermostat had not changed a single degree.

[AB]

Definitely check the constraints of the fan when hot as above mate, Phill had exactly this issue.


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[the evil twin]

Mightn't hurt to 'burp' the cooling system either in case of an air lock... nose uphill, cap off

[rusty_nail]

replaced the radiator today at mudskis direction. his logic was i knew the radiator was blocked at one stage and they never go back to 100%. i drove it round for 20 mins after installing the new rad and it didnt get hot. one thing that has me curious though, i spoke to a few people about the viscous hub today, and asked how it worked. its supposed to get stiff at operating temps? or only when the car is really cooking? after taking the car for the spin this arvo, i turned off the motor and the thing was pretty free, so maybe the motor just hadnt gotten hot enough? either way motor no longer climbing to boil so happy days!

[jay see]

My understanding of the coupling is when the engine is at operating temperature you should be able to spin the fan 1/4 of a turn with one flick. Of course with the engine OFF.

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[the evil twin]

You can't reliably test a viscous fan clutch by spinning the blade assy.

The viscous clutch operation relies on the centrifugal force of the belt driven part of the clutch pumping fluid into the shear plates.
The fluid port is controlled by the bimetallic spring operated valve.
When the driven part is stationary (engine off) there is no centrifugal force to pump the fluid into the shear plates even if the sensing valve is wide open.
Unless the engine is 'overtemp' the valve may only be partially open if at all

https://www.youtube.com/watch?v=UwM4OqsLek4

[threedogs]

Can you verify its getting hot with one of those thermal heat guns.
next Id run an extra earth strap

[PeeBee]

TD, whats the extra earth strap for and where would you locate it?

[MB]

You can't reliably test a viscous fan clutch by spinning the blade assy.

The viscous clutch operation relies on the centrifugal force of the belt driven part of the clutch pumping fluid into the shear plates.
The fluid port is controlled by the bimetallic spring operated valve.
When the driven part is stationary (engine off) there is no centrifugal force to pump the fluid into the shear plates even if the sensing valve is wide open.
Unless the engine is 'overtemp' the valve may only be partially open if at all

https://www.youtube.com/watch?v=UwM4OqsLek4

Cheers ET great video to learn properly their workings. I’m unsure of how mechanics properly test them mate if ever we need out there? Just saw this backyard yanky test though that could be a good unsafe method to make confetti or would it be ok if done carefully?
https://youtu.be/w-vI0ByaYP4


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[the evil twin]

Hehehe, yeah, that works a treat.
On my CRD I could stop it easily with little effort BUT that proves it is uncoupled not that it works.

The only way to prove it locks when installed is to get the engine hot, really hot.
The clutch isn't very progressive it goes from free to locked over quite a short temp range.
When my CRD was really hot you could tell if the clutch was locked as the fan noise and air blast left you in no doubt.
I wasn't game to try and stop it then.

You gotta remember these suckers work off the air temp flowing over them post Rad.
Hot coolant equals hot air but the clutch has no idea what the engine temp actually is.
My CRD often used to get up around 100 towing in the high 30/low 40's of the WA summer and I don't have any idea what the correlation to engine temp was but if I pulled over the fan would be roaring
If I had to guess I would reckon it was around 95 ish engine temp that the clutch began working but that is a wild ass guess.

It shouldn't work while the engine is 'riding' the thermostat in the low 90's... thats the whole point of decoupling the fan, save the horses and save the fuel.
Mine definitely did not lock up around my normal engine temps of 88 to 92.
I could stop it quite easily at those temps

Anyhow, that was my experiences, can't guarantee they are exactly what should be happening but seems to line up with most things I've read

[the evil twin]

... I might add that on the CRD I replaced the fan once over the years for cracks at the root of the blade near the hub (about 140K) and I replaced the clutch once at about 180K.