vw caravelle 2.6 overheat problem

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vwpumagt
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vw caravelle 2.6 overheat problem

Post by vwpumagt »

Hi Guys and Girls

Anybody familiar with 2.6 microbus/caravelle? I've got a problem in that she overheats.The fan comes on at times and then sometimes not.She'll boil at the back but the fan doesn't come on at that time or it would have been on, ran for a long while and then switches off even though the water is boiling at the engine side . Changed fan switches from different cars that works. The radiator is not old(2 years). I've checked for blockages, removed the thermostat(cut the spring out). Tried to bleed the system. Here I have no clarity. Tried raising the front and back alternately.When raising the front water will only come from the bleeding screw when she's boiling at the back otherwise nothing. Raising the back gives water sooner at the bleed screw. Head gasket/cyl head? no water /oil mix. no bubbling in water reservoir. Motor done over at beginning of year. She's ok when driving open road under 100/110km. Faster and she starts warming up.Traffic obviously. Sometimes the fan will come on and off all the time and sometimes it doesn't even though temp is above half. Any body experienced this nightmare?


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Re: vw caravelle 2.6 overheat problem

Post by Terry Phillips »

Take the kombi to Silverton Radiators and ask them to test the cooling system for any signs of co2 they should have the tester for that.
Once you are happy that there is no co2 in the system try bleeding it by pressurising the system with a hose pipe.
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Re: vw caravelle 2.6 overheat problem

Post by splitfan »

Make sure both the waterpumps are 100%
My biggest fear is that my wife sells my cars for what i told her they cost !!
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Re: vw caravelle 2.6 overheat problem

Post by fig »

I know nothing about your car or engine, but alarm bells started ringing for me when I read: "removed the thermostat(cut the spring out)"

The thermostat is an essential part of the cooling system. A faulty or missing thermostat can cause the symptoms you describe.
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Re: vw caravelle 2.6 overheat problem

Post by Terry Phillips »

I agree with fig,but if you do have to remove the thermostat on the road make sure you cut the center out of it and re fit the outer part that looks like a washer, or you wont have block pressure which is needed to cool the engine.
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Re: vw caravelle 2.6 overheat problem

Post by vwpumagt »

Thanks for the response guys
The water pump is new and the cutting of the thermostat came as an attempt to ease the problem but it will be replaced.I did only cut the centre.It's very confusing because sometimes only one pipe gets hot and that without a thermostat and one side of the radiator is warmer than the side where the switch is. I'll take your advice Terry and take it to silverton because its driving me nuts.
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Re: vw caravelle 2.6 overheat problem

Post by fig »

Overheating on Audi 5-cylinder-engined T3 buses has been a regular topic recently in The Sowetan motoring supplement's mechanical advice column. In today's issue an owner of one of these buses wrote in to say the problem lies in the additional water pump getting blocked. It seems not all of these buses had this additional pump, which was only fitted to buses with these engines, in response to overheating issues.
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Re: vw caravelle 2.6 overheat problem

Post by splitfan »

splitfan wrote:Make sure both the waterpumps are 100%
These busses were fitted with a electric inline waterpump have you checked that ?
My biggest fear is that my wife sells my cars for what i told her they cost !!
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Re: vw caravelle 2.6 overheat problem

Post by Terry Phillips »

splitfan wrote:
splitfan wrote:Make sure both the waterpumps are 100%
These busses were fitted with a electric inline waterpump have you checked that ?
You are never to old to learn,I was not a wear that the 2.6 had 2 water pumps but I am no VW fundi,I also seem think it has a flow issue.
I fitted a Toyota 2ct to my T25 camper with a caravelle radiator and never really had a problem with overheating,a diesel runs hotter than a petrol engine so the temp runs a bit high but even towing it does not overheat.Some guys fit a second ford v6 water pump in line but I have no need to go that route.
Good Luck lets hope it is a easy fix.
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Re: vw caravelle 2.6 overheat problem

Post by vwpumagt »

Yes it has two pumps. A small auxilary inline pump which is busted. It links the inlet line with outlet.Not sure which way it pumps. I just made a bypass linking the two pipes it fits into. I did consider its importance otherwise why would it be there.... right? But the thing is my cousin has the same van and his is bypassed with no problems. Some guy on another forum just blocked off both ends and no problem. It seems like a blockage or airlock because there was a time when the hose leading to the radiator at the front of the van was cold while the other was warm and remember there is no thermostat. At times it seems as if one side of the rad is warmer than the other where the switch is.
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Re: vw caravelle 2.6 overheat problem

Post by IMPI »

A small point of note on modifying systems in cars: If the factory could have saved 2 cents on each of the cars they build they would. so you can be sure that each part fitted has some significance somewhere. That inline pump is not a by pass it is there to cure the chronic overheating these cars had when new. thermostats on todays cars are vital imagine saving 75 bucks each on a million engines quite a bit eh.
Before you search for a fault ensure that the whole system is as designed The fact that one side is hot some times shows me that your water is not circulating properly and by having a faulty pump just confirms that. Check for a blocked rad especially if you didnt have a coolant (anti freeze) in the system.
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Re: vw caravelle 2.6 overheat problem

Post by vwpumagt »

I totally agree with your thinking Armand. Will start there and see what happens. Thanks everyone, will let you know if I find the cure.
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Re: vw caravelle 2.6 overheat problem

Post by Bugger »

We have sorted out a few 2.6 busses and just bought a 2.5 with broken engine that we repaired
I had over heating problems on 2 of them they do tend to run hot
Who did the engine for you ?
Was the head skimmed ? if so how much ?
Was the head re chamberd / CC`d correct ?
How sure you are the Newish radiator is not blocked with sediment at the bottom rows as we had that problem once aswell that the water do not sirculate properly at the bottom of the Radiator as the Thermal fan switch is located at the lower part of the Radiator
Or Bring it to us and we can check it out and solv the Problem for you
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Re: vw caravelle 2.6 overheat problem

Post by vwpumagt »

At this point Pierre, your offer to bring it to you is just what I need. Alas I am in Cape Town. The head was repaired( it was corroded at some water channels) and skimmed and pressure tested about 6 months prior to this engine overhaul(this was a rebore, new pumps etc.) Your observation about the radiator has me going. I'll be taking the car to silverton for testing as soon as possible.Chambered/ CC'd ?? I don't know what it means. The engineers just did the normal things.I WAS told that the head won't be able to take another skim.What other symptons will an overskimmed head have ? The motor does take the normal time(quite long) to reach operating temp. When I drive her steadily at 100 kph she stays cool but if I push her the temp will eventually start climbing.Stop/start is a no no. I am just trying to give you guys as much info and hoping someone will put it all together.I am obviously holding thumbs for a simple solution.
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Re: vw caravelle 2.6 overheat problem

Post by retrovan »

vwpumagt wrote:...................I am obviously holding thumbs for a simple solution.
This purely sounds like a Air-block to me.

Have you had someone stand and fill the radiator, while the engine runs,
and you open all the joints , one by one,
allowing the air to bleed out from all the little hidden spots.
Loosen the clamps, and twist the hose, let the air out, and some water,
Do this with someone ensuring the radiator stays full to the brim,
with the engine running,
and while it leaks water on that joint, clamp it again,
Do this with the bleed valves as well.
When its done, and not overheating, pour in the anti-freeze, slowly, as it has a higher SG then water it will sink to the bottom, displacing the water, so you do not have to drain water to get the anti-freeze in, and again have air introduced.

Hey! worth a try.... :roll:

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