940 Turbo Heater Control Valve

[Forrest]

I discovered the other day that the original heater control valve was starting to leak on my 1994 Wentworth after 28 years and 275k miles. I wonder whether this might have been a factor in the drivability problems I was having a year ago since its failure mode is to spray the distributor with hot liquid.

Anyway, I replaced it today with a Professional Parts Sweden all plastic jobby bought earlier in the year from eBay for £20. I’m sure this is nowhere near the quality of the original but it’s better than one that’s falling apart - literally, see photo.

This was actually quite a straightforward job despite the ridiculous location Volvo chose to install this part. I didn’t replace the hoses which are also original but appear to be reinforced, unlike the emergency spares I bought recently from Skandix.

The heater valve is in the lower of the two hoses to the heater matrix. I found disconnecting it at the firewall and then pulling the whole caboodle through to the inlet manifold side of the engine the easiest way to gain access without any dismantling beyond removing the transmission fluid dipstick.

In order to remove the original hose from the heater matrix for the first time in 28 years I first cleaned up around it to remove grime and traces of dried coolant. I sprayed a bit of maintenance spray onto the jubilee clip and then fully loosened it and pulled it right out of the way down the hose. I then gently twisted the hose from side to side using Knipex pliers adjusted to grip it gently without crushing anything and got it started by gently prising with a screwdriver. It then slipped off really easily with no damage to either hose or spigot. Phew!

For reassembly I first attached the short (downstream) hose to the valve and tightened the jubilee clip and then assembled and aligned the remaining connections and tightened them in situ. I found the original rubber vacuum connector too loose a fit on the new valve. It is a tight friction fit on the hard, white plastic vacuum pipe and can be pulled off. I replaced it with a short length of 1/8” ID braided vacuum hose.

[360beast]

What a coincidence, I have had a slight coolant leak on my 940 ever since doing my engine swap and it tuned out to be the heater valve was leaking, so on Thursday I went to undo the jubilee clip and it crumbled just like yours. As I needed the car for the Friday evening I just ordered an all plastic no brand job from euro car parts for £10.xx and picked it up Friday morning.

While I was there I found the reason for my hesitation under load which I suspected but never made time to look at until I did the valve. My distributor oil seal was peeing out oil and had soaked the inside of the distributor and all of the electrical contact points. So I cleaned it all up and fitted a distributor I have been meaning to fit for about 6 months that has new O-rings, oil seal and fibre washers, I'm very happy to say it appears to have cured the hesitation.

I will be ordering a half metal half plastic one from IPD to keep ready to go if needed.

[Forrest]

Is there any indication what brand those cheap ones from Euro Car Parts are? I thought the Pro Parts Sweden one seemed fairly good for what it is but to replace it in my stock of spares I’ve ordered a couple of these which I’ve seen mentioned on the Forum. Not sure if anyone has actually fitted one though.

https://www.ebay.co.uk/itm/353107355735

Was the distributor doable without removing the engine from the car? There never seems to be much room there.

[360beast]

Originally Posted by Forrest

Is there any indication what brand those cheap ones from Euro Car Parts are? I thought the Pro Parts Sweden one seemed fairly good for what it is but to replace it in my stock of spares I’ve ordered a couple of these which I’ve seen mentioned on the Forum. Not sure if anyone has actually fitted one though.

https://www.ebay.co.uk/itm/353107355735

Was the distributor doable without removing the engine from the car? There never seems to be much room there.

The picture shows it labelled as Scantech (aka scamtech for poor Chinese parts) but it has no label on the part or the box and the only indication to the brand is EIS (on the receipt) which after I googled it appears to be a German company.

Yes I did my distributor with the engine fitted, a bit overkill to remove the engine to fit a distributor

If you think there is no room back there try working on Rolls Royces and Bentleys and you'll think the room at the back of the head is a luxury!

I use an 8mm spanner for the middle and O/S bolt for the cap and an 8mm ratchet for the N/S bolt, pull the HT leads off and the king lead before removing the bolts. Then it is just a case of removing the rotor arm and the two 10mm bolts and pulling the distributor out, it is usually a bit stuck as chances are it hasn't been out for over 20 years.

I was surprised at how many American cars also used the same heater valve which would explain why the A/C valves are so readily available, I didn't know Holden used them too. They link is cheaper than the ones from IPD so I'll buy one of those instead, thanks for the link

[volvo always]

My mysterious coolant loss was also the heater valve on my 940 turbo. Should buy another as a spare.

Cheap Ebay one fitted, so far so good.

Had more coolant loss later and was the oil cooler pipes. Not a bad job to do.

James

[Pete940]

Originally Posted by 360beast

new O-rings, oil seal and fibre washers, I'm very happy to say it appears to have cured the hesitation.

Maybe I'll have to send you a distributor one day! I broke mine attempting to get the little pin out. I wanted to change the oil seal & washers. Do you remember if changing these parts helped to reduce the play/wobble in the shaft?
I was wondering if one of the reasons for most 7/9 series with redblocks having slightly lumpy idles is due to the dizzy shaft wobbling around. Just a theory. I know there's plenty of other reasons that contribute.

Forrest, did you fit a left hand drive part? I can only see LHD versions online.

[360beast]

Originally Posted by Pete940

Maybe I'll have to send you a distributor one day! I broke mine attempting to get the little pin out. I wanted to change the oil seal & washers. Do you remember if changing these parts helped to reduce the play/wobble in the shaft?
I was wondering if one of the reasons for most 7/9 series with redblocks having slightly lumpy idles is due to the dizzy shaft wobbling around. Just a theory. I know there's plenty of other reasons that contribute.

Forrest, did you fit a left hand drive part? I can only see LHD versions online.

Yes the play is because of the fibre washers disintegrating allowing the shift to move up and down.

[360beast]

For those interested this is the valve I bought.

https://www.eurocarparts.com/search/...caAgUKEALw_wcB

It says it doesn't fit a 940 but it does.

[Forrest]

Originally Posted by Pete940

Forrest, did you fit a left hand drive part? I can only see LHD versions online.

The heater valve is the same for left and right hand versions with air conditioning. It is hidden under the distributor cap on RHD cars and is a bit more accessible on the inlet manifold side of the engine on LHD versions but it’s the same (vacuum controlled) valve.

The non-a/c version is completely different and apparently hard to obtain for RHD cars which use a “mirror image” version of the LHD valve. There have been various posts about this over the years. The favoured option seems to be a mod using a Mk1 Golf heater valve.

There was some talk a few years ago that Volvo Classic Parts might manufacture some more RHD non-a/c valves but I don’t know if that happened. All my Volvos have a/c.

[gpl1968]

I fiitted the plastic scantech version last time mine failed but was looking for one that looked like the original and found this on ebay:

https://www.ebay.co.uk/itm/122501307468?ssPageName=STRK%3AMEBIDX%3AIT&_trksid =p2060353.m1438.l2649

The pictures look remarkably similar to the oem Volvo part. Problem is they're in Australia.