Engine Cuts Out

[redboxerk9]

Camper was backfiring terribly therefore replaced the exhaust system as it was rotten. Has had a service but the mechanic mentioned the flat spot in the carb. A new engine had been put on by previous owner back in July last year. Sorry its 1.9 watercooled T25 DG engine.

Right, since the new exhaust the damn thing has not run right don't know if this is circumstantial or cause. Took it out for a drive on Saturday and after 11 miles the engine completely died - would not stay on until everything had completely cooled down (about an hour). Opened up the back and everything is extremely hot. RAC man came out and sprayed the carb and it turned over for a second or two but in the end we had to be towed. Have had the carb looked at and although a bit old seemed ok and my brother says the engine wouldn't just cut out like that with a faulty carb.

Ever since saturday it doesn't get very far down the road and the engine cuts out. Got the Haynes manual out, and have tested the thermoswitch which is faulty as the fans don't come on, so going to replace that. But whilst doing these checks the engine was only running for about 5 minutes and the water in the header was extremely hot, steamed when lid was loosened.

Going to order a new thermoswitch for the radiator fan, and probably thermostat just in case but is there anything else could cause this? All help gratefully received.

Many thanks
Sue

[redboxerk9]

or does anyone know of a reasonable mechanic in the South East London area

Cheers

[toomanytoys]

How have you tested the fan switch?? the fan wont come on until the gauge is reading at least 3/4.. this can take an age.. Now you havent said if the gauge is reading high or not.. is it??
You could well have a faulty thermostat, (use only genuine VW ones) where the engine is getting very hot but coolant isnt getting to the rad.. feel the rad when the engine is hot..

[andysimpson]

Thermostat and fan switch maybe faulty but can't be the cause of it cutting out, unless it seized. Did the RAC check to see if it is an igntion or fuel problem?

[toomanytoys]

True Andy.. I didnt get to the cutting out bit... (although isnt there supposed to be a "high temp cutout switch in the crossover pipe on the early DG for this purpose!! my velle has a sensor.switch there but doesnt seem to matter what you do to it, the engine doesnt stop..)

Could be the shut off valve on the side of the carb... they can work when cold then as they warm up break down and fail.. cutting the engine out..

could be coil breakdown.. but you would expect it to stuuter and miss heavily then stop.. or poss the ignition module (useually just fail though) or less likely hall sender but before wildly changing parts (unless you happen to have spares lying around (or pockets full on money), you have to do it logically..

[redboxerk9]

In answer to some of your questions.

The temp guage on dash doesn't show any sign of overheating. We checked the thermoswitch as per the Haynes manual, bridging with a paper clip and the fan kicked in.

RAC man checked that fuel was pumping through and all ok, but didn't check ignition.

It seems a puzzle that the water gets so hot so quickly. Is the Shut Off Valve on the Carb easy to find, diagnose/change?

Really appreciate all your help

Sue

[toomanytoys]

Bridging the wiring in the connector DOES NOT check the switch.. the rad has to get quite hot before the switch kicks in ie the temp on the engine needs to show 3/4 gauge..
If the engine is getting that hot and the gauge isnt showing it then the sender is at fault........

the cut off unit on the carb is an inch and a bit long cyl on the side of the carb with a single wire going to it.. its not easy to check its operation.. other than ensuring that voltage is going to it even when the engine cuts out..

Has the fuel tank been messed around with recently? new filler neck/cap etc?

[redboxerk9]

As far as I am aware the fuel tank has not been messed with, I only got it in October and previous owner had just put new engine in.

We thought we were checking the switch correctly, as the radiator fans have never kicked in even when it broke down. When we bridged the wiring the fan kicked in and was quite audible, something we haven't heard before.

Would the sender cause the engine to cut off if it is faulty.

Have had a quote from Southern Carbs for a new prototype Carb which will fit and its £300 or a rebuild kit £35, but would the rebuild kit be sufficient?

It just all seems strange that, although running a bit rough, she got us down to Clacton on several occasions, and Hastings numerous times just before xmas without a hitch, then after changing the exhaust has decided to die on us.

Is there a better manual for complete novices than the Haynes (more picture diagrams would be good)?

Cheers Sue

[Mocki]

you need to go back to basics..........

spark, fuel, timing, ect, before you condemn the carb........

as for the water getting hot, like Si said, is it getting to the rad at all, is it getting hot?

could just be a thermostat or blockage, could be a airlock........

too many varibles to diagnose at this distance.......

one thing at a time methinks.........you choose, we'll try and follow!

[clartsonly]

I think you timing was setup for the blowing exhaust and since you have compression the timing is too far advanced.

when my cracked exhaust was fixed I retimed it back to normal, as I advanced it to compensate for the knackered exhaust. with timing advanced the fuel explodes before the TDC and would therefore generate too much heat in the cylinders and also damage the engine.

[clartsonly]

But whilst doing these checks the engine was only running for about 5 minutes and the water in the header was extremely hot, steamed when lid was loosened.

Going to order a new thermoswitch for the radiator fan, and probably thermostat just in case but is there anything else could cause this? All help gratefully received.

I dont get this bit...
when you say header tank, do you mean expansion tank? the thermoswitch is in the radiator at the front of the vehicle, it takes about 20 minutes of running before the water in the radiator is warm, I assume you have made sure that the radiator fan works by bypassing the thermoswitch?

I would be concerned if you are getting alot of pressure and heat in the water quickly that the head gasket is on its way out. is it running really roughly, when it starts.

changing the thermostat is a nightmare, it is only a simple part but difficult to do, try opening the bleed valve instead to see if the hot water starts to travel around the water circuit. don't get paranoid that all of these things are wrong, sometimes they are just made that way

[redboxerk9]

Sorry yes did mean the expansion tank (where all the water is).

After the exhaust was fitted, it went to garage to be serviced and they said timing and mixture was spot on - and it was them that said the carb might need looking at but that was due to the usual flat spot. Could something have been unintentionally touched when putting the exhaust on? Sorry I am new, what's the TDC?

When we start it up it sounds pretty fine, misses slightly now and again but as I said we were only running it for about 5 mins yesterday and the water was steaming.

have phoned Southern Carbs and they say it doesn't sound like the Carburettor, but sounds like electrics - now I haven't a clue where to start


There are wires sitting all over the place, would it help if I took a picture and posted it on here.

Many thanks
Sue

[Mocki]

yes, a picture wouldnt hurt, might not help, but it might too!

[syncrosimon]

Just my simplistic thoughts.....

1. If the carb is at fault, then they usually just cause bad running, rather than no running what-so-ever. I have never been stopped by a carb problem, other than what toomanytoys suggested ie the fuel cut off switch.However when that goes, it goes and will not run at all.

2. Ignition problems tend to be more erratic, but will show up usually as poor tick over, miss firing etc, but can stop your vehicle.

.......

Describe exactly what symptoms your van has, how she runs, when she stops, how she stops, how it cuts out. This will help.

3. I dont think your coolant can be properly diagnosed until she is running right. The water pipes will be far to hot to touch, and will start heating up straight away. In the winter I have found that with the cab heater on, the main radiator will not get hot even after a 10 mile journey.

When did the van last run right??

[toomanytoys]

Where in London are you?? (PM me)

The rad fan will not cut in unless the rad sees very hot water.. you havent said if the temp gauge gets above half way or anything...

I am in W7/12 this weekend and could poss pop over (Sun) and have a look, got limited tools so unless you have a few might not be able to fix it, but ought to be able to find the problem...