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Hi all, I've recently got my B1 passat on the road for the first time and am experiencing possible overheating 'issues'. Basically, the temp gauge slowly rises all the way to perhaps 1 notch below the red warning area, sometimes peeking into this area for a few moments. It'll do this idling, and the rad fan will switch on periodically every few minutes. It rarely actually gets into the 'danger' zone though. Driving along, it will also sit very high up on the gauge, although motorway driving it sits perhaps 2 notches below red and feels stable. It's least happy town driving 2nd/3rd etc, but again still rarely touches the red zone, and only ever for a few seconds before either the fan kicks in or I turn the heater on. As a few things to mention; I've replaced the thermostat (opening temp of 87 degrees), replaced the water pump, done multiple reverse flushes and coolant system cleaner, replaced nearly every rubber hose, heater core switch/valve etc. All the hoses get hot and hot air gets into the cabin. I've also tested the stat in hot water and it opens at the correct temp. The Haynes suggests the fan switches on at 91 degrees, but I've temp checked (albeit with an Aldi digital thermometer) and it seems to be slightly delayed. I don't think I ever recorded more than 105 degrees in either the pipes, rad or block. Bottom hose sits around 85 degrees, top hose at 75-80, and the radiator around 80. When the fan turns on the rad drops very quickly to about 55-60. Now I don't know if these temperatures are normal (or accurate...), or if my gauge is misbehaving etc. Anyone got any advice or experience with hot old VWs? Also to note; the car has sounded and driven absolutely fine, i'm not losing any coolant, plenty of pressure in the system etc. Cheers and sorry for the essay  |
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1979 Mk1 Passat Estate 1.6 LS
1996 Mk3.5 Fiesta 1.3 Classic
1997 Mk1 MX5 1.8i
2005 Mazda 3 TS
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Sounds like it might just be a gauge thing. Your hose temperatures (apart from the 105ºC one) sound about right though I'm a little doubtful of the IR thermometers. Does the fuel gauge appear optimistic also? They are often fed from the same voltage regulator.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Check the wiring/spade connector at the sender. Not sure on the B1 specifically but most of that era its on the end of the head.
Sender will be cheap as chips to replace but old wiring may have built up resistance as it corrodes.I presume the fan thermo switch is standard VW in radiator jobbie. They can get a bit tired but town traffic should not get it cutting the fan in early.thermo switches are quite cheap as well.
The fact that air flow (motorway speeds) cools things that well may suggest a radiator/water flow issue. is it the original radiator?
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Needs a bigger hammer mate.......
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taurus
Posted a lot
Posts: 1,084
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Hi there Fred, I had the same with the Viva after a coolant flush, basically the rad was restricted. The flush had loosened a load of curse word that then got stuck in the rad.
You can try taking it off and using brick acid, vinegar or cheap coke to cleanse it. I'd look for a replacement rad if you can find one.
The rad may be flowing ok with a hose but any kind of restriction will cause the issue you're having.
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ChasR
RR Helper
motivation
Posts: 10,195
Club RR Member Number: 170
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If the rad is completely original I'd change that if a replacement can be found. It is surprising the difference a new rad can make!
That said if it is not overheating on the motorway (what speeds do you do?) the rad is probably OK.
I'd be tempted to get a new temp sensor and rad switch first however to make things more conclusive.
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These early Passats were well known for that. If it's the one I think it is with the roundish gauges in the dash. Take the speedo cluster out, there is a three pinned voltage regulator at the back of the cluster. Available from rs electronics/Conrad/ maplins. Replace it . Problem solved.
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Oct 11, 2016 13:21:55 GMT
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Does the fuel gauge appear optimistic also? They are often fed from the same voltage regulator. Nick Yeah it does. I've done just over 100 miles on my current fill up and the needle is still pointing to fuller than 1/1. On genuine full, the needle would go off the gauge if it could! However it does eventually drop down quickly when nearing empty and gives me a fairly decent indication at the last quarter (after 300-350 miles or so). I presume the fan thermo switch is standard VW in radiator jobbie. The fact that air flow (motorway speeds) cools things that well may suggest a radiator/water flow issue. is it the original radiator? Yes to both - the switch, from what I can tell, is sealed into the very bottom of the radiator. Looks relatively east to replace once the system is drained. You can try taking it off and using brick acid, vinegar or cheap coke to cleanse it. I'd look for a replacement rad if you can find one. Thanks, I'll maybe give that a go before buying a new one, although I think VW heritage might sell the same rad for the 1.6 Golf. Might need some playing about with plumbing but otherwise it looks right. If the rad is completely original I'd change that if a replacement can be found. It is surprising the difference a new rad can make! That said if it is not overheating on the motorway (what speeds do you do?) the rad is probably OK. I'd be tempted to get a new temp sensor and rad switch first however to make things more conclusive. Normally plod along at about 60pmh. Dash is this fella; (not mine but same type)  With heater on, town driving hovers by the top notch before the red. Motorway driving, it sits around 2 notches below the red. I'll look to replace the switches too. These early Passats were well known for that. If it's the one I think it is with the roundish gauges in the dash. Take the speedo cluster out, there is a three pinned voltage regulator at the back of the cluster. Available from rs electronics/Conrad/ maplins. Replace it . Problem solved. Dash above. No idea how to remove the cluster currently but I'm sure I'll figure it out! This will likely be the first thing I try and replace and test as it shouldn't require me emptying an only recently filled coolant system! Thanks all! I shall report back in due course with results/questions etc!  |
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1979 Mk1 Passat Estate 1.6 LS
1996 Mk3.5 Fiesta 1.3 Classic
1997 Mk1 MX5 1.8i
2005 Mazda 3 TS
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Oct 11, 2016 14:27:31 GMT
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Yep. That's the one I was thinking of
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Oct 11, 2016 20:39:39 GMT
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combination of the fuel gauge and temperature reading high points squarely at the voltage regulator, if the fan is cycling off and on there is unlikely to be a cooling system problem.
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These early Passats were well known for that. If it's the one I think it is with the roundish gauges in the dash. Take the speedo cluster out, there is a three pinned voltage regulator at the back of the cluster. Available from rs electronics/Conrad/ maplins. Replace it . Problem solved. Hi, Sorry to revive a thread from 2016, but I've just started looking into this again. Engine been running fine for 2 years but temp, fuel and speed all still over reading. I removed the dash last night and found the three pin voltage regulator, however it's a part that doesn't seem available anywhere, least of all maplins, conrad etc. Part number is 481957071. Anybody got any suggestions on where to find a new one? Or a suitable replacement? This is the regulator.  flic.kr/p/23WftysCheers for any suggestions! |
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Last Edit: Feb 1, 2018 20:18:05 GMT by arsonist
1979 Mk1 Passat Estate 1.6 LS
1996 Mk3.5 Fiesta 1.3 Classic
1997 Mk1 MX5 1.8i
2005 Mazda 3 TS
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Nope. That's not the beastie. It's a small three ,wire legged regulator. Will look for a photo ...
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Will look similar to this. About the same physical size too. Has a part number probably starting with 78..  |
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Last Edit: Feb 1, 2018 20:53:12 GMT by Deleted
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Will look similar to this. About the same physical size too. Has a part number probably starting with 78.. Regrettably, nothing at all on the back of the cluster that looks like that. Nothing else looks removable. Terrible photo as in a dark garage, but this is the back: flic.kr/p/22BQ5uDCan't seem to disconnect the wiring too so it's ib a very short leash from the dash! |
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Last Edit: Feb 1, 2018 21:51:35 GMT by arsonist
1979 Mk1 Passat Estate 1.6 LS
1996 Mk3.5 Fiesta 1.3 Classic
1997 Mk1 MX5 1.8i
2005 Mazda 3 TS
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🙁. Mine was a '79 and it had a dash that I could have sworn was the same. Always seemed quite funky as the green dails used to glow in the dark. I know the beetles used to have a thing like you posted,maybe an earlier type of regulator.? Maybe try on a Vw forum?
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Darkspeed
Club Retro Rides Member
Posts: 4,710
Club RR Member Number: 39
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Metal box type looks like a stock smiths type voltage stabiliser - Google it. They can be replaced/ modified to the type JB has indicated - plenty of info on the web with an images and all search.
Also worth a check of the alternator output see if its over charging or turn every electrical device on the car one and see if the temp drops.
I would say disconnect the alternator but thats usually followed by - never ever do that world will stop rotating and we will all float off into space.
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Metal box type looks like a stock smiths type voltage stabiliser - Google it. They can be replaced/ modified to the type JB has indicated - plenty of info on the web with an images and all search. Also worth a check of the alternator output see if its over charging or turn every electrical device on the car one and see if the temp drops. I would say disconnect the alternator but thats usually followed by - never ever do that world will stop rotating and we will all float off into space. It’s similar to the smiths one, but I think they are 9v and ze Cermans used 10v, Nein Nine v ...😂😂😂 |
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Phil H
Posted a lot
Posts: 1,448
Club RR Member Number: 133
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Overheating issue, Mk1 VW PassatPhil H
@philhoward
Club Retro Rides Member 133
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Smiths are an average 10V (it basically switches on and off but slowly) to generate it - which works fine with the heated bi-metallic strip their gauges are based on.
Not sure on VDO ones of that vintage - whether or not they're bi-metallic strip based or moving coil?
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jpr1977
Club Retro Rides Member
Posts: 656
Club RR Member Number: 18
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Last Edit: Feb 2, 2018 11:37:13 GMT by jpr1977
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