Importance of the good to cowl weatherstrip and the radiator air deflector?

I removed that cowl to hood weather strip a few years back because it was torn with the hood closed you can see into the engine bay just a bit maybe 1/2 inch or so by having g that open does it let hot air out or does it force air from the windshield into the engine bay? I’m thinking about getting another weatherstrip from LMR if it’s counter productive. Also I removed the radiator air diverter the black plastic dam with 4 push clips because my car is so low on the front end does this have anything to do with major cooling or would I be ok without it?


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The weatherstripping that seals the back of your hood on the front edge of the cowl is very important, your wiring harness runs along the backside of the firewall, without that seal water will eventually cause corrosion in the wiring

Air flows over the hood and naturally wants to get sucked in to your engine bay, that's why cowl hoods are so effective; having an engine bay without seals is fine on old muscle cars where there's half as much wiring that's all hidden directly under the fenders, too much wiring harness for them to do that anymore

Yes that seal I think I’m gonna get another because i have heard without it air blows in the back side of the hood and while driving under speed fights the air coming in through the radiator I’m not sure how true that is but it makes sense


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The air damn under the car is actually pretty important too. It scoops air up to the radiator.

venom1997 said:

Yes that seal I think I’m gonna get another because i have heard without it air blows in the back side of the hood and while driving under speed fights the air coming in through the radiator I’m not sure how true that is but it makes sense


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Most of your air for the radiator passes through the condenser

Which is why it's important people are conscious of the condition of it and the radiator's fins, clogged up with debris or smashed fins is no good

Whatever piece you took off from the bottom is fine, not needed; cars never had them for decades and today everything is completely covered up by plastic panels that blocks air flow, that way their 6 month old leaking Toyota timing covers and oil pans don't make a mess on their driveway

I doubt I will put my lower ones back on unless I have cooling issues

I_like_turtlez said:

The weatherstripping that seals the back of your hood on the front edge of the cowl is very important, your wiring harness runs along the backside of the firewall, without that seal water will eventually cause corrosion in the wiring

Air flows over the hood and naturally wants to get sucked in to your engine bay, that's why cowl hoods are so effective; having an engine bay without seals is fine on old muscle cars where there's half as much wiring that's all hidden directly under the fenders, too much wiring harness for them to do that anymoreView attachment 1835502

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I just realized from my own photo that someone left the harness plastic unplugged from it's dedicated spot, allowing it to rub against the firewall edge

Over time that tiny vibration will cause damage to the wiring, always pay attention to your harness routing, it does matter

Yeah I haven’t had any issues cruising around but it’s mainly a drag car now and I’m afraid at 130mph it will cause turbulence in the engine compartment I’m definitely going to put the cowl seal back on but may have to leave the lower dam off due to clearance


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Wow so did a little testing today on the rural roads by my house on a 5 mile stretch without the cowl/hood weather strip 70 degree temp 50 mph my coolant temps were 176-178. Came home let the car cool down and put the weatherstrip on. Redid the same test and same temperature outside engine coolant temp was 165-168 also IAT1 dropped as well I guess having that seal removed allows air to enter the back of the hood into the engine compartment and messes up the flow of the air through the radiator.


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Update I put on the air deflector and it was the same 70 degree temp and I ran the same route ECT was 164-166 so I’d say the air deflector is good for a good 3 degree drop the cowl to good seal was drastic difference all in all it made a huge difference 10-12 degrees


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