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Old 21st October 2019, 18:53   #1
Chunky2778
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Default Possible overheating issue/fusebox area fault?

Hi all, I've an 04 plate CDTi ZT that has basically not had the best of lives but should scrub up half-decent over time.

It's been sat for 3 or 4 months, driven 60 miles from where I bought it, started and ran every week, MoT'd and has been on the road for about 3 weeks.

Today I was pottering about trying to find my RCL fault and pulled each fuse to inspect. Must have put one fuse back in wrong slot as when I went out later the washers didn't work.

However first I pulled the bonnet and topped up the water and noticed that he'd spat some coolant. Nothing major, but enough to smell and sit in the ridges of the coolant expansion tank.

I've already done the thermostat mod months ago and it sits right on 9 o'clock, needle never moves once there. No signs of overheating either, and the level was fine.

Initial thoughts were the fan speed resistor (aircon doesn't work) but I read a few comments on here that said it's very rare for a diesel to get that hot to need the fan. The journey was nothing out of the ordinary, a little fast A road and some milling about some small B roads.

Is it possible something else runs off the fuse for the washer pump? Only other thing I've noticed is the coolant cap is ridiculously tight.

Do these suffer from head gaskets? Anyone ever had a cap go?

Also could someone remind of the procedure for getting the odometer to go into diagnostic mode so I can verify the gauge isn't faulty and read what the ECU is seeing temp-wise please?

My fear is there were a few wires with blue insulation tape around them near the fusebox and I've disturbed something.........
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Old 21st October 2019, 21:02   #2
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Hello Matt,


Quote:
Originally Posted by Chunky2778 View Post
However first I pulled the bonnet and topped up the water and noticed that he'd spat some coolant. Nothing major, but enough to smell and sit in the ridges of the coolant expansion tank.
Diesels typically run cool, but warmer with the in-line stat. Unless the engine's really working hard, I wouldn't expect it to get hot enough to expell coolant from the pressure cap. With a regular '140' cap, it needs around 120C or more to lift the valve. Of course, over-filling the cooling system is a different matter. If you top up the coolant so it submerges the header tank fins, it may well eject a little coolant simply from thermal expansion. The correct filling level is at the base of the fins.

Quote:
I've already done the thermostat mod months ago and it sits right on 9 o'clock, needle never moves once there. No signs of overheating either, and the level was fine.
Remember that the 'normal' mark of the temp gauge means the engine is anywhere between 75C and 115C. So not very useful at all.

Quote:
Initial thoughts were the fan speed resistor (aircon doesn't work) but I read a few comments on here that said it's very rare for a diesel to get that hot to need the fan. The journey was nothing out of the ordinary, a little fast A road and some milling about some small B roads.
Diesel fans typically spend their lives working for the aircon system. If you never turn the aircon on, the fan will probaby never come on from one end of the year to the next (except if it's worked hard as mentioned). I suppose the in-line thermostat may increase the need in warm weather. Whatever, you should fix the cooling fan. If it only requires the uprated gold resistor, get one from forum traders, eBay or electronics outlets. It's a relatively simple DIY job with plenty of HowTo stuff around here.

Quote:
Is it possible something else runs off the fuse for the washer pump?
No idea, but none of the fuses have an impact on the engine running temperature.

Quote:
Only other thing I've noticed is the coolant cap is ridiculously tight.
It shouldn't be that tight. It's only sealed by rubber gaskets after all. Overtightening eventually leads to bad sealing as the o-rings and sealing washer become compressed/mis-shaped. I'd suggest you get the cap replaced or at least renew all the rubber parts (see forum traders or eBay)

Quote:
Do these suffer from head gaskets?
It would be difficult to find a case here.

Quote:
Anyone ever had a cap go?
Often, See above.

Quote:
could someone remind of the procedure for getting the odometer to go into diagnostic mode
Section 7: https://www.the75andztclub.co.uk/for...ad.php?t=55585

Last edited by T-Cut; 21st October 2019 at 21:14..
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Old 21st October 2019, 23:14   #3
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Thanks T-Cut! That's really helpful. Glad head gaskets are rare, I think I may just buy a new cap and fingers crossed it doesn't happen again.

Only reason I thought possible fusebox area fault was it listed cooling system twice on the list I was reading, however I see now in the manual that's only for a Turbo model.

On a tangent but also kind of related note, I see from the diagnostic list you posted a link to that it's possible to read the VIN.

I'm after getting a key made as my RCL doesn't work and the guy I spoke to today said that it may be that it's had a drowned ECU at some point, if it has then the VIN in the ECU may not be the same as what is on record for key coding purposes.

Is the VIN I'd get up on screen one taken from whichever ECU is fitted to the vehicle or is it just written to the instrument cluster?
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Old 21st October 2019, 23:26   #4
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How much coolant are you putting in the header tank ? check the link below, also check the O-rings on the coolant cap are they flat?
https://www.the75andztclub.co.uk/for...77&postcount=7
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Old 21st October 2019, 23:56   #5
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Rather than a new cap replace the seals with Viton ones. If you do decide to replace the cap don't go for an Ebay one, I did that once and it was worse than the one it was replacing! Get the genuine article from a reputable supplier.

I was going to mention coolant level in the tank but Steve beat me to it with his link
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Old 22nd October 2019, 09:00   #6
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Quote:
Originally Posted by Chunky2778 View Post
On a tangent but also kind of related note, I see from the diagnostic list you posted a link to that it's possible to read the VIN.

Yes.


Quote:
I'm after getting a key made as my RCL doesn't work and the guy I spoke to today said that it may be that it's had a drowned ECU at some point, if it has then the VIN in the ECU may not be the same as what is on record for key coding purposes.

Is the VIN I'd get up on screen one taken from whichever ECU is fitted to the vehicle or is it just written to the instrument cluster?

If there were VIN mismatches across different control units, it would be made obvious when you turned on the ignition. You ought to ask about this in a separate thread. There are plenty of people who can give you advice who may not read this particular thread.


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Old 22nd October 2019, 10:55   #7
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Thanks Arctic, yeah I've overfilled it when I did the thermostat mod then......

I've ordered the Vitron seals anyway though as I thought the cap should never be that tight, my knuckles crack when I'm opening it which is never a good sign!

T-Cut, I tried the VIN display today, the last 5 digits matched my VIN plate so fingers crossed it's just a dodgy key but I'll do as you recommended and start a thread as it might save me a 70 mile round trip.

As an aside, I don't seem to be able to select option 7, it just resets back to the odometer. Also, I had an option 1.7 which isn't listed on your link?

Are there different levels of cluster?
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