T25 1.9 Water Cooled running hot

[leggydaz]

Hi, I hope someone can help us here - we are a bit stumped.

Our 88 T25 started running hot on the gauge and not tripping the fan so we checked around and have tried several efforts to fix.
So far we've replaced thermostat, and housing, fan switch (on radiator) and finally the temp sensor at the engine end.

But it still remains a problem - the van is running warmer than normal and the needle climbs to a point beyond where it has been historically, but it does not trip the fan as it used to.

Any ideas ? any help.... please.

[dbz864]

pull the plug of the rad (behind the small grill) short two of the connectors together the fan should run, if it dosnt the fault lies in the wiring not the switch. However you say its running hotter than normal, is it getting hot when driving (not stuck in traffic)? Where does the gauge sit when driving in normal conditions?

[ermie571]

radiator blocked?

When its upto temperature, have a feel of all hoses...make sure they are all warm. Whip the grill off and feel the radiator...is it uniformly warm/hot?

have you got the small belled ring around the top of the engine bay (think its early vans?) - if so, is that blocked?

No expert - just tips I've picked up from here



Checked the fuse????

[Ralf85]

Assuming all the other points are not an issue, have you been driving it regularly? Have you changed the coolant recently? Have you noticed any leaks anywhere? If there is a leak then you may have an airlock. Is the heater working ok?

[leggydaz]

Thanks all. I will try to respond to all in one post.

The van is used regularly and coolant was replaced earlier this year. There are no leaks noticeable.
Previously the gauge was sitting just a nadge to the left of 12 o/c. The fan would kick in if it went anything much over the needles width past 12 o/c

The van now sites around 1/3 to 1/2 between 12 o/c and far right.

The issues are found when the van is moving.

The heater seems ok. Hot air etc

My mechanic (normally fine) has shorted the fan and tested it works.

Any more ideas before I go feel my hoses?

[CovKid]

Radiator switch - almost for sure. Cheap enough to replace and if you are quick, you'll barely lose any water. Those switches were one of the most replaced parts on T25s at VW dealers. They have a hard life.

[dbz864]

Which temp sender did you replace there is 2 in the thermostat housing?

[leggydaz]

Which temp sender did you replace there is 2 in the thermostat housing?

Hi, thanks.
Apparently the sender feeding the gauge, not the warning light. Make sense? That's the tech's response to me.

[leggydaz]

Radiator switch - almost for sure. Cheap enough to replace and if you are quick, you'll barely lose any water. Those switches were one of the most replaced parts on T25s at VW dealers. They have a hard life.

Hi thanks. First thing I replaced! No effect.

[dbz864]

im presuming you are thinking its running hot because the gauge says so? Sounds a daft question I know. Shouldnt really be getting that hot when driving around at this time of year, has it overheated ? Have you checked the rad is hot all over? Have you checked for air in the system\?. Ask the mechanic which sender in the thermostat housing he changed the one pointing forward or the one pointing to the near side? You say you shorted the connections together off the fan switch and the fan works, so if the new switch you fitted is a good one it should work, presuming the water is at a temperature to make it work, you are presuming it is by the gauge, which is feed by the sender, so id check he has changed the correct sender.
Did it start getting hot after you had anything done to the van.?

[leggydaz]

im presuming you are thinking its running hot because the gauge says so? Sounds a daft question I know. Shouldnt really be getting that hot when driving around at this time of year, has it overheated ? Have you checked the rad is hot all over? Have you checked for air in the system\?. Ask the mechanic which sender in the thermostat housing he changed the one pointing forward or the one pointing to the near side? You say you shorted the connections together off the fan switch and the fan works, so if the new switch you fitted is a good one it should work, presuming the water is at a temperature to make it work, you are presuming it is by the gauge, which is feed by the sender, so id check he has changed the correct sender.
Did it start getting hot after you had anything done to the van.?

Thanks again.
Quick update: I removed the bleed ring tonight and cleaned out each "T" etc. One was indeed near blocked.
So refitted, bled and ran around for a bit. The gauge sits at about 1 oclock - and sits there.
So it is not massively overheating, but previously the fan would have activated by this point previously.

The issue came up just out of the blue - no other work had been done.

Like you, I suspect the sender - particularly if the fan switch seems happy enough with its temperature at the front.

I will check whether it was Front or Near side pointing sender. Just so I don't have to scurry back here and check - which is the one that controls the gauge?

Cheers

[leggydaz]

im presuming you are thinking its running hot because the gauge says so? Sounds a daft question I know. Shouldnt really be getting that hot when driving around at this time of year, has it overheated ? Have you checked the rad is hot all over? Have you checked for air in the system\?. Ask the mechanic which sender in the thermostat housing he changed the one pointing forward or the one pointing to the near side? You say you shorted the connections together off the fan switch and the fan works, so if the new switch you fitted is a good one it should work, presuming the water is at a temperature to make it work, you are presuming it is by the gauge, which is feed by the sender, so id check he has changed the correct sender.
Did it start getting hot after you had anything done to the van.?

Thanks again.
Quick update: I removed the bleed ring tonight and cleaned out each "T" etc. One was indeed near blocked.
So refitted, bled and ran around for a bit. The gauge sits at about 1 oclock - and sits there.
So it is not massively overheating, but previously the fan would have activated by this point previously.

The issue came up just out of the blue - no other work had been done.

Like you, I suspect the sender - particularly if the fan switch seems happy enough with its temperature at the front.

I will check whether it was Front or Near side pointing sender. Just so I don't have to scurry back here and check - which is the one that controls the gauge?

Cheers

[dbz864]

from memory its the one that points to the front. Its not unusual for gauges to sit slightly to the right .

[leggydaz]

from memory its the one that points to the front. Its not unusual for gauges to sit slightly to the right .

Thanks. OK, for the sake of a sender if the one changed is nearside we'll try the forward one.
As regards the gauge being to the right, I can accept that it's acceptable - but when previously it was near 12 oclock I feel I need to understand (fix) the reason why.

[G Dub52]

This is interesting as I have a similar issue, my van used to run at 12 oclock and now runs closer to 2 oclock when warm.

I think I will follow this thread through also to find a fix

I assume this is a fairly common issue judging by the amount of feedback.