89 1.8 Carb water temp too high

Hi, new to the forum and hope someone can help.

I recently purchased a 89 1.8 Cabby carb'd in blue and I am working my way through the problems.

I replaced the cambelt and tensioner, water pump, thermostat, coolant temp sender, fan switch and expansion bottle cap.

It started first time and then I set it up with the timing light. I set this up to the diamond mark on the flywheel but I am not sure if I needed to set the timing light to 17/18 degrees advance or leave it at 0???

now onto my issue, there was a problem with the temp gauge when i purchased it as it was reading high but the car did not feel like it was overheating. I flushed the system and replaced the coolant and followed the tutorials on this forum on how to bleed it.

When driving, the gauge sits at 3/4's (should be around 1/2?) and when standing still ticking over, the fan kicks in as the gauge maxes out/red light comes on (should kick in at 3/4's?) I have checked all the wiring and all seems fine. The only thing I can think of is it being a faulty gauge?

Any help would be really appreciated.

Cheers

Has your car got the three sensors in the coolant flange on the front of the head? The black plug and black sensor are for the temp gauge. Has it got a black sensor fitted(not another colour fitted by mistake).Are the wires ok, they tend to break and touch by the plug. You could use a separate thermometer to see what the engine temperature actually is. You can look up what the resistance specs are for the sensor. If all that checks out, it may be the gauge itself.

The brown haynes manual has some good advise on how to test your gauge using resistors and how to test your voltage stabilizer.
 

Regarding your timing, is it the EX engine code? Set the timing to 18 degrees(the diamond) with timing light at zero or 18 degrees advance on light and set to TDC. Don't quote on me on this because I've yet to find a definitive answer myself but from my research you leave vacuum advance connected.

The gauage sits steady when moving, increases when standing and triggers the fan. Doesnt boil over. Sounds like its working as designed with pos a slightly over enthusiastic sender/gauage.

Hi Steve1973, thanks for the reply.

Yes, I have the black housing with the 3 sensors mounted with spring clips. It previously had the black coolant temp sensor fitted and I replaced it with a new black one but still the same.

Wires seem good, I have removed the plug and checked continuity to the dash plug and all is fine. everything else on the dash works ok.

Just seems like the gauges is out of scale somehow?

As for the timing  I have done it both ways. I do have to say though it seems to run better setting the timing gun at 18 degree advance.?

Hi Early-1800

Yes the gauge holds steady but sits around 3/4 - 7/8 when driving. when standing and left ticking over, the gauge goes past the max and the red light comes on but the fan doesn't kick in till after the light has been flashing for 15-20secs.

The gauge just seems off scale somehow. Want it to be reading right as when the engine does over heat I won't know till it is too late.

Cheers

R1ckyD said

Hi Early-1800

Yes the gauge holds steady but sits around 3/4 - 7/8 when driving. when standing and left ticking over, the gauge goes past the max and the red light comes on but the fan doesn't kick in till after the light has been flashing for 15-20secs.

The gauge just seems off scale somehow. Want it to be reading right as when the engine does over heat I won't know till it is too late.

Cheers

The MK1 gauges are analogue depending on electrical resistance heating up coils and moving pointers and triggering flashing LEDs. Compared to modern digital displays and pointers using stepper motors driven instantly by ECUs by the time the pointers moved and you've noticed it will be too late.

Does it actually get into the red on the gauge or has the red LED ever flashed when running?

Could be a bad earth to the clock set. There should be an earth wire that goes to the corner of the rocker cover. Right hand side, back corner. If this is missing or bad it plays hell with the temp guage.

Other than that it could be the wrong sender. It'll read and trigger the fan but doesn't read 'correctly'. I had this on mine and I changed out the sender for a different one. I can't remember what I changed it for though. Sorry

Ian

Hi R1ckyD you should have two marks on your fly wheel. A dot which is TDC and a diamond which is 18 degrees BTDC. If your timing light is set at 0 then set the timing to the diamond. If you dial in 18 degrees on the timing light then set the timing to the TDC dot. Both ways you have set the timing identically. The advance on the timing light is for when you have no BTDC mark or want to adjust it to your own spec. I think you might already know all this though.
Here's a pic out of the manual explaining the gauge.

Thanks for the replies guys 👍

Hi Early-1800

When I turn the ignition on the led flashes a few times then goes out. I then start the car and the temp gauge gradually rises over to max then after the red led starts flashing the fan kicks in. The red led has never flashed while running. Only when ignition is switched on and when it gets to max.

Hi Ian,

I only have 1 earth to the rocker cover and that goes to the carb. Should there be another earth going from there to the clocks? If so do you know where does it attaches to the clocks?

The sender was initially a black one which I replaced with a black one. I have ordered another sender which should arrive today just incase to rule that out.

Hi Steve,

Thanks for confirming that about the timing. That is how I have done it 👍

I will try and carry out the tests as per the info you have sent if I can manage to get my head round it 🤪

Thanks again guys.

There are 2 earths, one should also go from the Valve cover tin left rear corner (right as you look at it) to the Coil Bracket nut.

Also you didn't say if your Fan works,  These little critters do a great job, however…..

The Radiator Fan cooling switch controls the Fan cutting on/off, and usually after a good run it would kick on at 95-105C as the heated engine will spike.

So I would suggest a couple of things.

Apply Power to your Fan and verify that it is running by jumpering 12VPositive to the Red wires as I don't know if yours is a 2 speed or a single speed fan.

The other issue I have seen is that the Fan Switch in the Radiator goes bad.

Prior to removing that switch as you have to Drain, Remove the t-stat and replace the cover and flush and back flush the cooling system. Replace the switch if it tests bad as you have to place it in boiling water with a meter attached to see if it picks… As well as a new t-stat.  

If your upper radiator cover or shield is missing as well as the rubber covers on the shroud, when the fan kicks on you can re-cycle engine compartment air over the Radiator and exacerbate the issue as the engine air isn't cut out of the Circuit and only allowing cooler outside temp air over the system

see: Radiator Fan operation explained? :) | Volkswagen Owners Club Forum

For my take on the operation.

Then how I flush the radiator..
How-to-flush-your radiator | Volkswagen Owners Club Forum

Hi briano1234

Thanks for the info. There is defo no earth from the back left corner to the coil bracket nut so will sort that out.

As for the fan, its a single speed fan and when linked the fan runs ok. I have fitted a brand new fan switch and tested the old and the new one and both are good.

However…….this morning I started taking the inlet manifold off to replace the gasket and o-ring as i know these can also cause issue's. 2 of the bolts that hold the inlet manifold on had been mangled and i couldnt do anything with them so bit the bullet and removed the whole head as i thought while i have some time on my hands i could change it and have the head pressure tested more as a sanity check. Good job i did. The gasket has gone in 2 places and all the little water ways in the head, the gasket and the block are blocked. This makes me think that my temp gauge is actually reading right and that the flow of water was just not getting through the rad to the fan switch. Just took the gasket and head down to the local machine shop and he is pressure tesing and skimming the head for me today. He looked at the head and gasket and said no wonder i was having problems with heat because the water could not flow properly.

Going to have to drop the oil anyway as there bound to be water contamination in there now so might change the oil pump also.

Fingers crossed once all back together most of the issues will be resolved.

I am now in need of some new parts, gasket set, head bolts, studs etc. Where is the best place to get these from as i want decent stuff. Also on one the mounting points on the inlet manifold it is cracked. Hasnt gone into the actual manifold but would like to get a replacement but not sure where to look.

Also have a few issues with my carb, the 3 point unit is not woking has power but wont retract as well as the overrun solenoid and the auto choke plays up. Have any of you or know anyone who has done the weber conversion? Are they a good upgrade?

Sorry for the long winded post. 🙈

Thanks again to everyone for all your help. Nice to know i am not alone 👌