half an hour holiday (overheating)

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Ok, got it.. measuring on 20k ohms (?)

Key only: 0.72

Engine running cold: 0.47

Engine running end of white block: 0.18

Engine running temp gauge on half: 0.11
LHD 1989 Diesel 1.7 somewhat homebrewed

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

just as a sidenote, red indicator light on dashboard doesn't seem to come on at all (even with coolant sensor unplugged)
LHD 1989 Diesel 1.7 somewhat homebrewed

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937carrera
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Re: half an hour holiday (overheating)

Post by 937carrera »

OK, so the next thread to look at is this one

https://club8090.co.uk/forum/viewtopic.php?p=8225128

Translating your readings what you are seeing is

Cold - 470 ohms

Warm, end of white block - 180 ohms

Temp gauge on half 110 ohms

Now according to VW the reading for the transition area is 510 VW1301 units which converts to 265 ohms. There's no directly comparable reading but 265 is between 470 ohms and 180 ohms, so seems an appropriate value.

For the half way point, you are seeing 110 ohms, which is between the 180 ohms and the reading at the top of the range for overheating which is 50 VW1301 units or 34 ohms.

Looking back at the Samba thread your values seem sensible, except that at the mid point you are seeing 110 ohms, when a value of about 67 ohms would seem to be more sensible.

I'm thinking that the sensor is out of spec, but it is likely to give a lower needle position than expected, which is a bit perplexing.

Usual drill, make sure the connections for the temp sender are clean and the voltage stabiliser for the dash is working correctly, it's all in that thread

It may be worthwhile retesting with the meter set to 200 or 2000 ohms range

Also check the resistance on the earth side of the connector to a good earth - should be very low
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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937carrera
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Re: half an hour holiday (overheating)

Post by 937carrera »

https://club8090.co.uk/forum/viewtopic.php?f=39&t=165511&start=75

110 ohms seems to correlate to 88 degrees


..... and reading on, including some of my previous posts, the concentration of the coolant has an influence too, so I supect your sender is actually fine.

Maybe getting some resistors could be a good cheap diagnostic, I assume your holiday week is over now :(
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Thanks for plugging away, will have a good read through tonight.

So currently no coolant as wanted to test the system first, so water only.

Could still make a break for it if everything comes together - kids off until early September, maybe a bit closer to home though!
LHD 1989 Diesel 1.7 somewhat homebrewed

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

still chipping away, cleaned all the battery terminals as they were pretty filthy. Went for another run and similar to before but the heating took longer (also a lot cooler weather).

Bled again on a slope after the run and a bit of air but nothing major.

Couple of small squeals again at the beginning of the journey, so I'm thinking I still need to tighten the belt or look at the water pump perhaps?
LHD 1989 Diesel 1.7 somewhat homebrewed

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

still chipping away, cleaned all the battery terminals as they were pretty filthy. Went for another run and similar to before but the heating took longer (also a lot cooler weather).

Bled again on a slope after the run and a bit of air but nothing major.

Couple of small squeals again at the beginning of the journey, so I'm thinking I still need to tighten the belt or look at the water pump perhaps?
LHD 1989 Diesel 1.7 somewhat homebrewed

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937carrera
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Re: half an hour holiday (overheating)

Post by 937carrera »

Put a new belt on ...... not expensive and eliminates that from the diagnosis.
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Thanks, like your thinking.

However, I had someone I know who is a mechanic look at it today as he was visiting Brighton.

He revved the engine a lot, got some dreaded white smoke and pretty quickly diagnosed it as a head gasket issue. He knows T25s so trust his opinion. The stuck thermostat seems to be most likely what caused it.

So next step of the journey, which is to get it to a mechanic. Just to say thanks for all the help and support, brilliant forum! I sure know a lot more know than I did a week ago about water cooling systems and electrics and really appreciate the altruism.

I have also managed to finish the install on a split charge leisure system,  as well as fitting a fridge and cooker, rear door seal and other bits from a 'donor' van over the course of the past three weeks.

Feel kind of 'all dressed up with nowhere to go' currently. Hunt for the elusive available T25 mechanic continues tomorrow..

Onwards!

 
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937carrera
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Re: half an hour holiday (overheating)

Post by 937carrera »

Oh well, it's always important to confirm the diagnosis and not jump feet first into the most complex and expensive solution.

The good news is that it's a marginal fail at the moment, so the chance of more major damage is reduced.

If it makes you feel better I had a mate come over with a car (non VW) for us to look at to see if it should be MOT'd. I booked it in, was about to take it round but when the engine was started it seemed a bit smoky. Anyway, after cancelling the MOT, taking the cam cover off and re-torqueing the head down the conclusion is that the HG failed as he was driving to see me.

This one was different, coolant causing a misfire, loads of steam on tickover, apparently clean running at 3000 rpm. Same failure, different symptoms, but we could see bubble going into the header tank.

Why can't the guy that diagnosed it fix it for you ?
1981 RHD 2.0 Aircooled Leisuredrive project, CU engine
1990 RHD 1.9 Auto Sleeper with DF/DG engine

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Thanks, yes and best of all is when I do get it to a mechanic it won’t be done blindly.

I wish he could but he only visits a partner down here a day every week or so, otherwise works full time in Kent and hasn’t got the time to work on it
LHD 1989 Diesel 1.7 somewhat homebrewed

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Haven't given up, and after having had to endure the pain of paying to hire a car for a brief trip to Wales (where we lucked out with sunshine) it is back to digging and delving around the wiki and forum while I wait to get this to a mechanic (still like mining for gold around this way) and trying to level up my knowledge a little..

I found this post https://club8090.co.uk/forum/viewtopic.php?t=149310

"A failed 'Dalek' cap either allows free flow of coolant which can blow out of the vent holes in the top-up tank OR not allow pressure to be released which leads to a blown header tank or the weakest link in the cooling system being blown apart ... that can be a hose, a coolant pipe or the thermostat housing. ... To test your Dalek cap take to off and (after wiping it) blow down the spout, there should be a kind of toot as the valve opens to allow the air through it."

Mine certainly doesn't make the tooting/quacking noise as is so beautifully demonstrated here:
https://youtu.be/RT8Ew43mNg4

and the coolant blowing out the vent holes was exactly the case. New one ordered from Brickwerks...



 
LHD 1989 Diesel 1.7 somewhat homebrewed

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redsnapper
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Re: half an hour holiday (overheating)

Post by redsnapper »

Dalek cap changed, seems to be better but temp still creeping as soon as I hit the motorway, didn't expect it to fix it, just trying to get the bits I can tackle in order.

As you suggested 937carrera, going to aim to change the belt, more tinkering while I wait really but aiming to get other bits in order to try and eliminate what could have caused the failure in the first place if that makes sense.. Anyone know the procedure for a KY 1.7 diesel or a good guide to change it? I've had a good look around the wiki and manuals online, but all the diesel ones I've found are for the 1.6td which has a different system.

Thanks!

 
LHD 1989 Diesel 1.7 somewhat homebrewed

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