635 passes emisions in NY but not MA

You really need a full readout of the car's emissions as this can point more accurately to any problem. Taking one in isolation doesn't give a clue.

Ok.

massachusetts readings: HC grams per mile = 00.82 - Limit = 02.00 CO grams per mile = 012.04 - Limit = 030.00 NOx gramps per mile = 05.44 - Limit = 03.00 CO2 grams per mile = 436.18 - Limit = N/A

New York readings: HC = 0.55 - Limit = 0.80 CO = 4.69 - Limit = 15.00 Nox = 1.19 - Limit = 2.00

Hope this additional information can help clarify.

Thanks! Dru

Dave Plowman (News) wrote:

If the CO readings are outside spec the HC and NOx will be effected. That usually indicates a wrong mixture. For a small variation, check things like the air filter and minor air leaks to the induction system.

Does anyone with this make car have their 2005 readings in either state? Just wondering what another '86 with approx 160k on it reads in MA or NY

Thanks! Dru

Dave Plowman (News) wrote:

On Wed, 21 Sep 2005 23:27:17 +0100, "Dave Plowman (News)" waffled on about something:

Could this be caused by using some slightly substandard fuel, or even a change in altitude?

Dodgy

Just have it retested somewhere else in MA. The shop is either trying to bilk you out of some emissions repair work (likely) or has faulty emissions testing equipment (less likely). One question... was there any difference in the engine temperature when you had these two tests done? Had you just driven all the way to New York vs. just down the street to the MA station? Having the engine completely up to temperature may help you pass the next attempt in MA.

Or you could do like so many of your Mass neighbors and get a fake address (or a summer home) in New Hampshire and register it up here, since we don't need no steenkin' emissions tests (yet).

I helped a guy in CA with a euro 635 that wouldn't pass. Told him to put some alcohol in fuel. He got methanol from a racing supplies store and I think he had a tank with about 2 gallons of petrol and one of methanol, worked a treat :-)

Jeese. Now that sounds a little scary!

Thanks for all of the replies so far. I'm still fishing for someone who's actually just had their 635 tested in MA.

In answer to Matt's question:

This car runs hot like a bastard in neutral. So in Mass, The needle was just shy of the overheat mark when it was tested. It was July 6'th and a hot, hot summer day. Don't know how that affects the test. Also, I'm guess Boston and NYC are about the same altitude.

In NY, the test was done at 9am. Ambient was about 65 degrees, car was only run about 1/2 mile in NYC midtown traffic. My guess is the temp was prob exactly on the money as far as heat.

Thanks again for all the responses so far. I really appreciate the enthusasm...and I so badly want to keep this car on the road. I love it so!

Best! Dru

John Burns wrote:

Don't seat it Dru. We'll keep that car on the road by hook or by crook. It might have to sit in my driveway, but it'll be on the road ;-)

Now, I might be inclined to figure out what all the overheating is about... Not just for emissions reasons.

I'm pretty confident the overheating is caused by a not-so-great aftermarket radiator. The original radiator's "nipple" cracked at about

90k. You know, the little nipple that sticks off the top left of the radiator where the overflow hose connects. Very poor design on the OEM. Anyway, I replaced it with an aftermarket german brand and its always idled hot, and ran hot up long inclines.

So I'm betting its the radiator becuase I've heard if the car overheats in idle that's almost always the radiator. I've also heard speculation that it could be a fan clutch...but I thought fan clutch symptoms were limited to high speed overheats. This car runs at normal temperatures at highway cruising in low altitude.

All comments welcome on this.

I guess another potential temperature cause would be the aftermarket CAT that's on it. I bought that CAT from Bavarian Auto Sport about 5 years ago. I'm thinking that if the CAT isn't designed for enough airflow that could cause a heat buildup.

Really I'm open to any thoughts on either of these two causing an issue with overheat, and still looking for comments on specific MA emissions tests from a similar car this year.

ps. I've already had the thermostat replaced (not necessarily with the lower celcius on though) in an effort to cheeply remove that as a possible cause of running hot.

Bear in mind the car has never, ever over-heated. It'll just creep up to just below the over-heat mark on a hot summer day in idle, or stop and go traffic.

Thanks again guys. I love this car and continue to put mechanic's children through college in an attempt to keep it on the road :)

Best! Dru NY/MA

Malt_Hound wrote:

No - the fan clutch effects low speed stuff. At higher speed the airflow takes over. You could remove the fan totally if the car never dropped below say 30 MPH. But you should hear it working - as the coupling progressively locks up the fan runs faster and makes more noise.

The other possibility is a faulty waterpump. A blade missing from the impeller would make a bigger difference at low revs.

No, you have it bass-ackwards. It's actually quite logical. If it overheats at idle but runs cool at highways speeds then the fan clutch

*is* a prime suspect. This is because you are forcing air through the rad when at higher road speed so the fan is really not required.

OTOH if it runs cool at idle but overheats at highways speeds (or overheats all the time, at idle or at speed) the radiator is suspect. This is because we are getting enough cooling airflow through the rad (we know this for a fact at highways speeds), but the heatload produced by the engine is too much for the poor heat exchange capacity of the faulty radiator or substandard water pump, etc.

CATs don't have airflow, only exhaust flow. I would not be looking at the exhaust as a reason for overheating.

I'd put in a lower temp t-stat and replace the fan clutch. Also look closely at the fan blades to be sure they are all there. They have a habit of breaking off which would give similar overheat at idle condition.

Any tips on diagnosing either fan-clutch or water pump problems? I'm tempted to replace the current after market rad with a certified BMW one as it is...but now it sounds like maybe its either of the other two as well.

Thanks! Dru

Malt_Hound wrote:

Well,

You could just remove the water pump and inspect the impeller. The normal failure mode is a seal and/or bearing failure, but some BMW water pumps have plastic impellers that fragment and become less efficient pumps. I don't believe that yours would be plastic based on the model, but hey... who knows? And removal / inspection would be free. Also inspection of the fan blades would be free.

To test the fan clutch is tough since the amount of resistance it presents is supposed to vary with temperature such that at higher engine compartment temps it is harder to turn (slips less) and gives more air flow. If you are really strapped for cash you could try to figure out a way to seize the fan clutch. Maybe drill a hole in it and fit a screw through. You really don't need the fan to slip, it's just there so that it saves some horsepower when the fan's not needed and allows the engine to come up to temp a tad quicker.

Hmm. I'd caution against this. I don't think the viscous coupling ever

*fully* locks, and the fan running at full engine speed all the time might cause water pump bearing failure through vibration if high revs are used. And then there's the noise...