Just because the OEM valve is "all plastic" and "looks like" the ScanTech valve does not mean much. Plastic what? If it's cheap injection molded polystyrene, it may last a year. If it's glass filled reinforced polymer, it might last a decade. The material and forming specs make all the difference. Volvo does spend a lot of time on these and that's usually why the OEM parts last much longer. Take radiator and heater hoses as a good example: compare OEM with MTC. An aftemarket producer can always knock the parts off using the same dimensions but that's about all that is the same.
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See the 700/900 "FAQ" at the menu bar top screen left side.

I have to put on my manufacturing hat.

1)Injection molded parts, a 6-8 mold die, several sets and run it quick and hot to maximize capital equipment. The hotter incoming injection side of the plastic is probably the side that was broken. The hotter the plastic the faster it flows and the weaker it gets. Even the part-metal broke at the hot crimp. A cheaper plastic grade does not help. Maybe a high regrind percentage too. Also no long term testing was done or was required by Volvo and other buyers. To bad for us.

2)Why all plastic now. The old part-metal is finished with zinc and yellow dichromate. This is the best general rust proof finish you can get next to hot dipped galvanized and it is cheap to plate with yellow dichromate. Dichromate is considered a carcinogenic in Europe and not easily recyclable. The US will likely follow if they haven't yet. The now defunct cadmium plating has been removed from manufacturing for 25-30 years too. Now, the only Ford/Volvo heater valve like this will be all plastic, especially since the valve is used in Europe.

Get the part-metal while available, smaller mold and less heat needed to flow a shorter distance.

Tom

Maybe we should just add Heater control valve to the bi-annual maintenance list
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89 240 wagon, 94 940, 200K, 94 940, 135K

I would never use scan tech for anything important unless there was no other alternative. They are known for shoddy quality control. I imagine the Volvo one is built to a better standard.

Four seasons switched from the old style to a new design. It is also used on a lot of domestic models as well. I think it is less prone to issues. Most of the local retail parts stores will have this model.

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Paul NW Indiana '89 744 Turbo 160K/ '90 745 turbo 140K

Dear spasske,

Hope you're well Please explain, in detail, "Four seasons switch from the old style to a new design". What is the "old style"? What is the "new design". Does this change have to do with materials (metal versus plastic or one plastic versus a different type of plastic)? Does this change have to do with the design of the valve, in terms of its shape, etc.?

I believe "Four Seasons" makes climate control items, e.g., blower motors, air conditioning evaporators/condensers, etc.

Thanks for your help.

Yours faithfully,

Spook

Somehow lost the picture in my previous post when I edited it:

http://www.rockauto.com/getimage/getimage.php?imagekey=161462&imageurl=http%3A//images.wrenchead.com/smartpages/partinfo_resize/DUS/15-5812.jpg


Paul NW Indiana '89 744 Turbo 160K/ '90 745 turbo 140K

You can get a superior heater valve by ordering Motorcraft (Ford) part no. YG-136 from Rock Auto for about $18. Picture here: http://www.rockauto.com/catalog/moreinfo.php?pk=380367

This was used in a lot of Ford cars, trucks and vans in the 70's and 80's.

This substitute has been mentioned by others on this board, and the one I have looks identical in exterior appearance to the Volvo unit except that most of its body is metal, much like the leftmost one in your photo.

The FAQ suggests the same course of action. Unfortunately, there are no pictures and I didn;t want to end up with another plastic unit.

I was thinking that the plastic unit would be decent if someone put a sleeve inside... Will order the ford one as suggested. I've got a simple bypass connector in the "emergency bag" but I'd rather have a part I can trust.

The old valve lasted at least 15 years and around 240k before it failed. $20 is worth the investment. Just hope I get the good one.

Thanks to all who weighed in!

I'd like to know if there is any glass particles in the broken plastic tube. The glass would often create a matte finish on the plastic but not always.

240 owners are putting up with some of the same problems.

More on 940s:
heater control valve 1991 940 se

Please post back on how you adapt the vacuum hose, if it is a smaller diameter.

Tom

Dear RepairmanJackal,

Hope you're well. A replacement valve failing so quickly could be a freak event.
With plastic or rubber items, it is not obvious how the material has been processed. As a result, we cannot learn much by looking at such items, unless they have standard markings. Even then, if too much or too little of an ingredient has been used, we'll not know this. Sometimes a minor variation in an ingredient or processing temperature can greatly affect durability.

When you install the replacement valve, be sure that the hose - into which the valve is placed - is not "twisted", such that the ends of the valve are being "pushed" in opposite directions. This could happen, if the ends of the hose has to be twisted to seat it onto the hose nipple at the head or at the firewall. That twist-stress could accelerate valve failure.

To ease hose installation, lubricate the inside of the hose with a small amount of dish-washing liquid. This should allow the hose to be pushed straight onto the nipple.

Hope this helps.

Yours faithfully,

Spook

I have suffered the same problem with an all-plastic replacement valve I got from a local supplier. It lasted about a year. Switched to the "top-hat" style but am apprehensive as it has been less than a year. On the bright side, it looks to have the matte finish associated with glass reinforcement. Will probably look to get an original style from Rock Auto as a backup.
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1999 E320 1994 F150 (awaiting a new engine) 1989 560 SL 1994 945T (daughter's) 1986 242Ti (awaiting a B230FT transplant) 1968 GT500KR (under slow restoration) 2007 HD Nightster (son's ride)

I got a few of the part-metal valves from FPCG and Swedish Engineering 6 or 7+ years ago, the same as the Ford part. One leaked from the onset from the metal crimp to the plastic. FCPG made good by replacing it. I thought there was a gasket between the two but is was just a hot crimp that didn't conform.

I think you might see this part-metal design going to the all plastic once existing stock is depleted, Ford and Volvo. Must reduce manufacturing costs and increase profits.

This is still subject to the tube breaking but on the opposite side or at the crimp. My thoughts is that the all plastic would be fine if it didn't degrade with heat. If the part metal is available it may use a more reliable plastic.

This was in a box marked MTC.

Tom

My Motorcraft YG-136 looks exactly like that picture, except that the vacuum stub looks to be a smaller diameter and is straight - no bend.

The box is a Ford Motorcraft with both the Ford and M/c part no's and the fine-print claim: "Designed, engineered and recommended by Ford Motor Company".

Notice it doesn't also say "manufactured". No country of origin shown.

I put a ford one on mine years ago no problems. I walked into the local parts dealer with the Volvo one in hand and he said that looks the same as a Ford one.
So Fords are good for something.