engine and drivetrain Are heat shields necessary?

[nbristow01]

Just curious. Saw nothing specific in the archives. Never in my muscle car days have I ever seen heatshields on exhaust. Just headers, plug wires right next to them, and everyone is running fine. I am into the 02s now and it seems everyone has heat shields. just curious if there is an 02 specific reason to use them? i know it evacuates some heat from the engine bay but not that much. plus if you run a cold air induction setup (alos rare i see on 02s) then you don't have to worry about the heated air being taken in in the first place.

please give me some feedback on this if you can

[esty]

i believe the purpose is to prevent the plug ends or wires from touching the the exhaust and melting....

[Guest Anonymous]

I've run no heat shield on stock manifolds and headers for the past 20 years with zero problems.

[ray_]

Hearsay says that oil leaks from the valve cover and other areas can catch fire if the heat shield is not in place. Why risk it?

Cheers,

Ray

[DanOKC]

Some folks just use the 318i gasket/heatsheild by itself, vs the original cast metal or sheet metal part. It does deflect some heat from the plug wires, but yea, you can run without any heatshield. There was on most of these cars a pre heat tube that attached to the heat shield & it used the heat from ex manifold to pre heat the air going to the carb for winter. When most folks swap out the solex for a weber & use the small weber filters, they ditch the preheat stuff, if it isn't already gone.

I remember getting scolded by a BMW mechanic one time for not having my heat shield in place :-)

Here is a link to pic of the 318 gasket.

http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,332471/highlight,318i+exhaust+gasket/

[Scott Sislane]

I found it to be a huge PITA and removed it. Getting your plugs out & back in... If you keep your wires up & away from the manifold, they seem to do fine.

[TobyB]

I run them on both our street cars,

and the race car gets the 318 gasket.

I had all sorts of plug wire problems until I did it,

and now I don't. It makes my life a lot easier.

t

[osbourne]

Just curious. Saw nothing specific in the archives. Never in my muscle car days have I ever seen heatshields on exhaust. Just headers, plug wires right next to them, and everyone is running fine. I am into the 02s now and it seems everyone has heat shields. just curious if there is an 02 specific reason to use them? i know it evacuates some heat from the engine bay but not that much. plus if you run a cold air induction setup (alos rare i see on 02s) then you don't have to worry about the heated air being taken in in the first place.

please give me some feedback on this if you can

Let's see now......the engine on your old "muscle car" would probably last at least 10-15 minutes at continuous full power operation before developing much bigger problems than burned plug wires. Your 02, on the other hand, is capable (or at least it was, when maintained to original specification) of sustained full power operation for far longer than you can stand it. Under those conditions, you can bet your sweet ass that the exhaust manifold gets hot enough to damage plug wires & connectors. That's why BMW put that heat shield on. They didn't do anything of the mechanical nature just for looks. It's all about function. That's why BMW became such a great name in the first place.

BTW, although may have been taken off & discarded by a previous owner, that little plastic box on the radiatior "bulkhead", with the hose leading to the air cleaner......sure does work like a cold air induction set-up, if you lock the little lever in place ("summer" setting) the way BMW intended.

Please keep in mind that anything BMW put on the 02 was put there for a good reason, and only after doing sufficient research & development work on it. It is good that you have enough sense to make inquiries about a mechanical part before you remove or modify it. Hopefully, from this forum, you will get the information you need to make an educated, rational decision.

[nbristow01]

Thanks that was the kind of response I was actually looking for. I will kep the heatshield. I do not have the plastic air box. I have a aftermarket weber airclean from the previous woner. I have been looking for an aftermarket cold air induction set up specifically for the 02. On JAMS site they have the adapter to mount on top of the carb with a 2 1/2 inch inlet for a 2 1/2 inch hose. I may look for a new airbox from a newer bmw with filter in it to adapt

[osbourne]

Thanks that was the kind of response I was actually looking for. I will kep the heatshield. I do not have the plastic air box. I have a aftermarket weber airclean from the previous woner. I have been looking for an aftermarket cold air induction set up specifically for the 02. On JAMS site they have the adapter to mount on top of the carb with a 2 1/2 inch inlet for a 2 1/2 inch hose. I may look for a new airbox from a newer bmw with filter in it to adapt

Here's some food for thought: First of all, I need to tell you that although I've owned 02s since 1971, I do not claim to be an 02 guru. I'm far more comfortable offering advice on MGs and Porsche 356s. However, I'm going to offer a suggestion and I'm sure some of the 02 gurus on this forum will chime in with their related views. Oh, yeah. Confession time: I've never had much use for Weber carbs on street-driven cars.

Instead of the Weber, why not go to the Solex carb fitted to mid-'72 and earlier 02s? I offer this suggestion with the following points in mind:

1.) The larger carb (a Zenith, I think) fitted to the mid-'72 & newer 02s was, I think, larger for the purpose of helping the poor, increasingly emissions-strangled engine retain some "beans". If this is the case (and I'm confident that it is), the original Solex carb will provide you with plenty of performance, along with generally better drivability.

2.) With the above in mind, I would back-date to an earlier carb & manifold with (and this is key) a re-curved distributor to give spark timing based upon the engine's performance needs rather than an advance curve that is, ahhhh......emissions friendly. The right advance curve will do more for the all around performance and drivability of your 02 than any other single item.

Speaking of ignition: It's always been my opinion that, on street-driven cars, the engine really doesn't give a rat's butt how hot the spark is.......it just cares about when the spark occurs. So, don't waste your time with some "atomic fireball" coil or CD system. Just plain old points & coil will provide the greatest reliability....although you do need to give them some maintenance now and then.

As far as the air box goes, you should be able to scrounge one from a salvage yard, or one of the vendors on this forum.

None of the above should be taken as gospel for the 02......just my personal opinion gained from a lot of hands-on experience with other cars over the past 45 years. I hope this is helpful to you and that it generates some good, technical dialogue here.

[02Les]

According to the parts books, heat shields are used on ti, tii, Turbo and USA '02s. So if you have a Euro carb'd '02, you don't need one.

Probably why my '74 Touring doesn't have one.

[Retrogroucher]

It's also helpful to protect any rubber/urethane parts (bushings, motor mounts, etc) from exhaust heat. I may make some when I redo my '02 depending on proximity to header/exhaust.

[c.d.iesel]

Are heat shields necessary? = y e s

[Emyers]

1.) The larger carb (a Zenith, I think) fitted to the mid-'72 & newer 02s was, I think, larger for the purpose of helping the poor, increasingly emissions-strangled engine retain some "beans". If this is the case (and I'm confident that it is), the original Solex carb will provide you with plenty of performance, along with generally better drivability.

Good food for thought, small point however, all non ti/tii were equipped with Solex carbs. The early models using the one barrel while the later two barrels used the Solex 32/32 DIDTA. The six pot models used versions of the Zenith.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

[osbourne]

1.) The larger carb (a Zenith, I think) fitted to the mid-'72 & newer 02s was, I think, larger for the purpose of helping the poor, increasingly emissions-strangled engine retain some "beans". If this is the case (and I'm confident that it is), the original Solex carb will provide you with plenty of performance, along with generally better drivability.

Good food for thought, small point however, all non ti/tii were equipped with Solex carbs. The early models using the one barrel while the later two barrels used the Solex 32/32 DIDTA. The six pot models used versions of the Zenith.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

Thanks for the enlightenment, Earl. When they were new, I never paid much attention to the two barrel carb equipped models, as I had moved on to a Tii by then.

What is it with the two barrel Solex that makes a switch to a downdraft Weber attractive? I would guess it has to do with the choke arrangement, but, to be honest, I've never held one of those '02 two barrel carbs in my hands, let alone rebuilt or tuned one.