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over the summer there was quite abit of discussion on by-passing the flapper since many of them were locked sucking HOT air all the time.mine was,and i had a concern that when winter rolled in that i may have a start/warm up issue with it pulling in constant cool/fresh air when below freezing.that has not been a problem at all.starts right up and doesn't stumble what so ever.after leaving the driveway i have to go 6 miles before the 1st traffic light so that probably helps.just passing along my experience.
--
92-965-211k, 94-965-215k, 92-944t-205k, 83-242dl,totaled(8/04), 84-242GLT,totaled(2/03),83-245GLT,retired(03)
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make sure that you still have air flow when blocking off the hot side.on the 94 the fresh air side diameter is larger than the hot side.
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92-965-211k, 94-965-215k, 92-944t-205k, 83-242dl,totaled(8/04), 84-242GLT,totaled(2/03),83-245GLT,retired(03)
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While I had my car apart changing the head gasket I noticed my flapper door wasn't closed to the hot side even though the garage was easily above the advertized operation temperature.
When I went to the dealer to get a new one, they couldn't find it in the parts computer. I even took in the one from my car to see if we could get any number's off it. NO GO. I've ordered one like the one in a 850 for which they had a part number and the air box looks very similar. If it works I'll publish the part number.
If it doesn't work, I'm going to disable mine as well. Probably leave the pipe in place to fool the emissions police.
--
'96 965 with 16' wheels at 121K. Had '85 745 Turbo Diesel for 200K.
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i'm not second guessing the engineers,this little item regardless of price,is failing(with regularity) and taking with it some high dollar components.since i dont have any driveability issues i will continue without it.when i checked the wifes 960 it had already been bypassed also.when they fail it keeps the flapper on the hot side cooking the AMM and maybe even the power stage modules on the intake.i'll take my chances.if i do sell this car,which is highly doubtful,i'll inform the next owner.
i'm not the 1st to bring this up,it's been dicussed for years.i'm merely passing on my experience and not recommending any one else do the same.
--
92-965-211k, 94-965-215k, 92-944t-205k, 83-242dl,totaled(8/04), 84-242GLT,totaled(2/03),83-245GLT,retired(03)
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Two power stage modules failed in my 92/960 before I found the malfunctioning thermostat in the air box. First I thought that the alternator was overcharging, because of bad bearings and scratchy noises of the electrical parts. I changed the alternator and blocked the hot air in the air box. I am convinced now by all the talking here that this bad air box design was the cause of my problem. I have three Volvos and all the thermostats are a bit different from one another. I found my 93/940 to have the best design and works very well. Better so than my newer 96/960.
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Let's try to straighten out a couple of (IMHO) misconceptions.
The airbox preheater has nothing to do with improving cold starts. Common sense tells you that after sitting all night at 0F, there is no heat anywhere to "preheat" anything. It's only AFTER the engine starts that the exhaust manifold starts to heat up, and then starts warming the air going into the airbox.
The main purpose of the preheater arrangment is to improve emissions after cold startup. Fuel (even coming out of a high pressure fule injection system) vaporizes better in warm rather than cold air, and combustion will be improved. Secondarily, when driving in extremely cold weather, there is probably a slight improvement in fuel economy, and maybe a possible benefit to throttle plate icing tendencies.
Faster warmup? doubt it...can't see how the small amount of warmer incoming air (with its extremely low heat capacity) is going to speed the warmup of a 400-lb lump of iron and aluminum which is combusting fuel with 1000+F controlled 'explosions' at several hundred to the minute.
--
Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and numerous old motorcycles)
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For $8.70 including Shipping, taking 5 days to get here from Scrotum, Connecticut, I could not resist to make it right.
From what I know or think I know, the purpose of the Wahler Air Box Thermostat is to maintain a constant 70 deg Inlet Temperature.
If it was not a problem, then why did the engineers bother?
It all boils down to Air Fuel Ratio. Inlet Air Temperature affects that ratio, as the air molecules become less dense or more dense. If your fancier or newer Volvos have an AMM, Lamba Sond (O2 Sensor), and Computer for adjusting timing and mixture, then everything affecting Air Fuel Ratio should be working, as designed, to make that engine operate efficiently, in my opinion and meets EPA specifications.
That is one thing that bugs the shiite out of me when I go shopping for a second hand car. Previous owners whom think they know better than the automotive engineers or are too cheap to replace parts or add funky alarm systems or wires outside of the wire bundles that were obviously added. The first place I look after I get beyond the nice paint and dent free body is under the hood. If it is greasy, grimy, missing parts or b.s. parts added, I will not even give the car a second thought, because I know what it would cost to make it right.
Hopefully, you guys will be the one and only owners, until the day it meets the wrecking yard and your cars won't be flogged off on some poor, unsuspecting, naive bugger who doesn't know anything about your cars, until he starts reading.
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the one and only purpose of this thermostat is for warm up ONLY.if it sticks you're sucking hot air that will,in short order,kill the AMM to the tune of a couple hundred bucks.did you say you're from scrotum?
--
92-965-211k, 94-965-215k, 92-944t-205k, 83-242dl,totaled(8/04), 84-242GLT,totaled(2/03),83-245GLT,retired(03)
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posted by
someone claiming to be G James
on
Sat Jan 8 13:01 CST 2005 [ RELATED]
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The reason I sealed the airbox thermostat is that it failed in the partially open position, which is not a good design especially if it cooks the AMM. There is no warning and there is no easy check of its functionality. I decided to seal it when I found the flapper half open on an 85-90degree day.
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This is all very nice. I think that we all know that the purpose of the thermostat is to keep even temperature. In my case I can't find the thermostat by itself to replace it. I have to buy the whole air box. Now that is an engineering miscalculation or is it pure business?
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posted by
someone claiming to be tjts1
on
Sat Jan 8 12:24 CST 2005 [ RELATED]
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Just kidding. Were all entitled to our opinions.
The air box thermostat can only maintain a minimum temp when operating properly. If the outside air temm is 80, 100, or 120 degrees your intake will be breathing that same temp.
Second point. The AMM sensor also has a built in thermometer. Thats the metal bar just behind the heated wire. The computer uses that information to compensate its air mass readings for. Therefore the AMM is accurate at any temperature you are likely to encounter on earth.
The air box thermostat's only purpose in life is to shorten the amount of time the engine needs to reach operating temp. It reduces emissions at start up. This can become a real issue in extremely cold climates like Sweden for example. Not really an issue here in California where it never gets below 40F degrees.
I don't think anybody around here is going to be "flogged off on some poor, unsuspecting, naive bugger who doesn't know anything about our cars". Anybody that takes the time and effort (you included) to go online, researches and maintains their own 960 to over 200k miles probably know's what they are doing. I wouldn't hesitate to buy a car for most of the regurals in this forum.
Just wanted to set things straight if anybody does a search and runs across this thread in the future.
Justin
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I had the same problem with the air box thermostat in my car. I blocked the hot air and had no problems with cold engine. What surprises me most is that I have not seen any maintenance info on this part other than changing the filter. I had posted this message before. I will never know for sure what happened, but is just my opinion.
http://brickboard.com/RWD/index.htm?id=902115
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Agreed.
Cold air = more oxygen = happier engine.
--
Norm Cook Vancouver BC; 1989 745T 200,000KM
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tjts1,no,it wasn't me that did the temp checks,it mat have been dewfpo.i like your air intake,but here in Ky. we get plenty of rain and i dont want to soak the filter.you're brave to remove the AMM screens,it is after all,located after the filter which is good.
i've also installed a 940 turbo grill using the 960 chrome surround as you did.looks great,i've owned a couple turbo's in the past and like the black(dark metallic gray)grills.we both have white wagons and the chrome grill is just too much.i also like your sliding sideways shot in the wagon.i'm known for having a little fun myself.
--
92-965-211k, 94-965-215k, 92-944t-205k, 83-242dl,totaled(8/04), 84-242GLT,totaled(2/03),83-245GLT,retired(03)
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posted by
someone claiming to be tjts1
on
Sat Jan 8 06:51 CST 2005 [ RELATED]
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The evildoer (thermostat housing)
The accomplice (original intake)
The hapless victim (9 months living AMM screen free and counting)
Batman (aka the Home Depot intake)
Robin (MANN 2 stage filter)
This is a second vote for "Get rid of that airbox thermostat"
DM960, were you the one that did all those great measurements of airbox temperatures with and without the thermostat?
Justin
94 965
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"were you the one that did all those great measurements of airbox temperatures with and without the thermostat? "
That would be yours truly.
DEWFPO
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1998 S90 071,245 and 1995 964 154,100
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Of my and the kid’s four normally aspirated 940s, all flappers are nailed shut so that they get cold air all the time. There have been no issues in our common 20F mornings. There have been no issues in the few sub 10F days. The sole 940T does not have a hot air flapper.
After a couple years on the board, I have read only one comment purposing drivability problems that could be caused by throttle body condensation freeze-up.
If anyone wants to do this, I removed the air cleaner box, drilled thru the flapper and the exterior of the air box then used 10-32 hardware. I double nutted the screw because the plastics and rubber gasket on the flapper is too weak to support a lock washer compression. The modification can easily be reversed.
Side note: This is a very good time to remove the window washer bottle and motor, clean and rinse, clean and grease the terminals and check or replace the hoses. If you do this there is a complicated tangle of hoses with a vent hose and a check valve that has to be reinstalled in the same manner. Make a diagram before the hoses are removed.
--
Tom from NC, currently enjoying record high 70F days in Janurary.
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