confirm that some noxious fumes are entering the passenger cabinfrom the engine compartment through the ventilation intake grills, Iwas planning to tape up the gap between the hood and the rest of thecar (where the wipers are). If the hood gasket is no good at preventinggases from reaching the intake vents from the engine compartment, thenthe tape should help block this pathway. Of course, I will avoidtaping up the intake vents themselves, since I want fresh air fromthe outside.
I am concerned that when I peel back the tape, it will pull away body paint. My initial plan was to use packing tape. Is there a more advisable (less risky) tape to use for this purpose? I was thinking also of makeing my packing tape less ticky by taping onto some clothing before reusing the tape on the car. But this might be too much; some less secure tape might fly off on the highway. Thanks for any suggestions on this.
Even though the air pathway through the hood gasket is obstructed by tape sealant, there are smaller pathways through the firewall. Would it be right to assume that such leaks would be neglegible compared to the fresh air coming from the air intake vents?
The point of this 2nd question was to avoid a misconclusion. For example, if the fumes penetrating the firewall is significant, then a proper seal at the intake vents wouldn't block the fumes. I might think that it was adequately blocked, and since I would still detect the fumes, it would be easy to mistakenly conclude that the fumes were originating from some place other than the engine compartment.
AOL -- Ray saved me the trouble of saying it. But I would add: if the car body shop stuff is like that used by draughtsmen and artists, try not to leave it in place too long. As you will be wanting to take the car out on the road, in (bright? hot?) sun, be wary of heat making the adhesive extra tacky. Or have those cleansing potions handy. FWIW.
The hardware store had some less tacky tape for painting, so I weighed the benefits against those of regular masking tape. The latter being a more robust seal, especially in the turbulent wind on the highway. Since the ventilation/respiratory problem is quite severe, I opted for the regular (tackier) masking tape for a surer test. It turns out that was a good idea. This is because it isn't so easy to tape off the gap between the edge of the hood and the rest of the car. When the hood is closed, the edge of the hood rests /over/ the grooved section that leads up to the intake vents. "Grooved" is not so much the description as "ridged". Deep-ish rideges, oriented parallel to car's center-line, occuring half centimeter spacing across the entire left-right width of the intake grill (i.e. across the width of the windshield). Not a very tape-friendly surface for purposes of sealing.
To get around the problem of tape-unfriendliness, I opened the hood and looked at where the hood gasket contacts the hood. There is a bit of a ridge on the underside of the hood that mirrors the gasket, presumably the contact surface with the gasket. So the question I'm trying to test is whether that seal is being maintained during driving (or at all e.g. when car is still). I can imagine that during the force wind from highway driving, air from under the hood can force itself between the ridge & the gasket, and make its way to the intake vents. To hopefully prevent this, I put abutted rolls of masking tape along hood gasket. Seems to help.
I hesitate to say once again that I solved the problem because it also felt that way when I bypassed the coolant around the heater core. I think what happens is that I am healthy when the change is first made and being tested, and the effects of exposure to the fumes is mild. With prolonged exposure, the effects get more severe, and it takes less exposure to provoke lengthy spells of violent coughing. Then I say "enough", drive a few days with fan off, set to recirculate, and windows down, and get healthy again. The same thing probably happens when I hit upon the next idea to test.
I hope this is the real cause this time. I can try changing the hood gasket, though everyone who has looked at it says its good. If that doesn't solve it, I have to resort to creative thinking on what else to do. Having masking take rolls along the hood gasket is not a very good long-term solution. Rain will do away with it, as will constant opening/closing the hood (which I have to do the check oil, since it is still being lost at nonneglegible rates).
Just thinking laterally here: if that seal around the hood (uh, it feels weird saying that, as we say "bonnet" -- never mind) is in a state to seem suspect, I take it the car is not brand-new? If that's so, can you rule out the possibility of fumes coming in through combinations of breaks in the exhaust system and rusted- through holes in the floor (&c)?
I must say, you are the most diligent owner I've come across in a long time!
With the hood closed, check to make sure that the surface of the hood is even - flush with the surface of the adjoining fender both at the front of the fenders by the grille and at the back near the windshield. If not, the hood will need some adjustment. Start by turning the hood stops at the front of the car up or down as necessary. If the gasket appears to be in good shape - bulging along its length evenly and not torn or cracked, then go to a place sells adhesive-backed foam tape, like what you would use to winterize a home window or along the bottom of a pickup truck cap. Clean the surface where the hood gasket contacts, wipe with rubbing alcohol, and place the foam tape so that the hood gasket contacts the foam tape when the hood is closed.
The foam will not be visible when the hood is closed and won't look as Rube Goldberged as masking or duct tape.
Clarification below. Context: Need to use tape to block off possible pathway for noxious fumes from under hood, through hood gasket, and into intake vents (beneath wiper). Ridged surface makes it hard.
I didn't see this possible misinterpretation: I didn't put an entire "roll" of masking tape right on the hood gasket, as in a roll bought at the store (which weights one to several pounds). The "rolls are formed from 3-inch lengths of 2-inch wide masking tape, rolled like a cigar into a 3-inch long hollow cyninder of about 1-cm diameter. The tacky side is on the outside. These rolls are oriented parallel to the hood gasket, place side by side on top of the gasket. The ridge on the the underside of the hood closes down on the tape rolls, whereas they would normally close down directly on the gasket.
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