Engine Cover

[BigDiesel]

Was there a heat trap problem with the factory engine cover, as I have seen them taken off quite a bit.
I'm talking abou the gray plastic cover on top of the manifold that says "TURBO POWER" or something along those lines. Thanks
Dave

[AndyL]

Most people remove it. The cover can trap some unnecessary heat around the IP/FSD.

[TurboDiverArt]

I'd think that if you use a PMD/FSU relocation kit you can probably keep it on. I'm not sure but I'd think the actual Injector Pump can take the engine heat; it's the added heat from the PMD that kills it.

If not then I was thinking of drilling 2 or 3 1" holes in the front facing portions and possibly cut slits or holed in the sides. I like the way the engine looks with the cover on so want to retain it. The IP I would think should be OK without the PMD since it's being cooled internally by the fuel.

Art.

[MTTwister]

First reason to take it off was the mounting of First style of the FSD cooler - Blue Heat Sink. THe other option, from Heath diesel, is a larger Flat Plat of Aluminum that can be mounted elsewhere witht he extension wiring kit.

Thing to look for, when I had my IP replaced ( 35,000mi) it was suggested that I needed to replace my upper rad hose, it was starting to wear thin. Turned out that the Plastic shield was cutting into the upper hose where the hose passes under it! I ground out some clearance on the cover, and installed a new hose ( Checker Auto).

Take a close look at your Upper Rad Hose where it passes under that cover!

[TurboDiverArt]

I've had my cover off many times in the past few weeks and haven't noticed any wear. Just replaced the thermostat's last weekend in fact. I'll check the clearance this weekend.

Thanks for the advice.
Art.

[S\W Off Road]

The cover is not going to have any noticable effect on heat in the engine comartment, it only makes changing the fuel filter a PIA.

[TurboDiverArt]

Originally posted by S\W Off Road:
The cover is not going to have any noticable effect on heat in the engine comartment, it only makes changing the fuel filter a PIA. That and it looks good!

[gmctd]

The TURBO POWER cover was designed to look good, and as a positive ventilation 'duct' for the Inj Pump and FSD\PMD.

The front vertical slots, in a high pressure area directly behind the fan, allowed 'forced' air flow thru to the low pressure area at the firewall, ensuring positive cooling when the vehicle was in motion.

The slots continued from the vertical to the horizontal plane, allowing heat to rise, flowing cooler air from the rear opening and across the IP and PMD - supposed to prevent 'heat soak' when the engine was off.

The cover could also maintain heat around the fuel system in low temp months, under short tripping conditions - shopping, etc. Warm fuel makes for easier repeat starting.

No studies have been done on the relationship of the cover to FSD\PMD failures (note the number of failures on various 'heat sinks'), and there are many trucks still running with the cover installed, no failures, beyond what is normal for increasing age and high mileage.

I think the later covers, abbreviated at the upper intake plenum, were done partly as a styling change, partly due to the dual t-stat arrangement, but did expose the IP\PMD.
Rising heat could still draw cooler air from the firewall area, thru that short cover and across the IP.

Problem with that may be body design changes to insure close fit and proper alignment between body panels, fenders and hoods.
How and where is all that underhood heat vented out?

It was generally thought that heat from the IP, and 'heat soak', caused FSD\PMD failures (not FSD|PMD heat causing IP failures!), but Stanadyne and GM determined the IP to be best mounting location, and that design was never changed.

Other issues with that have been covered in many separate posts.

How about that 'snorkle'?
It was part of a high pressure fresh air source directly to the air filter box.
Ducted to the front bulkhead thru the fender, it ensured a constant ambiently cool air flow, around and past the hot engine bay environment.
Faster the vehicle moved, greater the forced cool air flow available. Ram-air, yes!

It was generally thought to be too small for a 400cuin engine, so most folks removed it, permitting road dust from the front tire to be drawn in thru the various cracks and openings in the fender assembly.

Actual measurements proved it to be adequate for a 400cuin engine limited to 3500rpm, where most power requirement is between 1700 and 2800 rpm.
Not much requirement for 1000cfm flow at those rpms.

The benefits, in my opinion, outweighed popular opinion, even without comparing 'snorkle' size to turbo compressor inlet diameter.

Cool, fresh, ram-air at highway speeds lowers intake air temps because compressor is heating air from, say 80deg instead of 180-up deg.
Cooler, denser intake air charge = more power, free.

If I had an '88-up truck, and were to remove the 'snorkle', I would have plumbed a piece of intake ducting from a '70s\'80s vehicle (some ducts were rectangular, some were oval, shaped) to duplicate that original fresh air path, using the 'snorkle'-to-airbox cutoff for proper seal.

So - Happy New Year, Folks......

[ 01-01-2004, 09:21 AM: Message edited by: gmctd ]

[JohnC]

Originally posted by gmctd:
It [the snorkle] was generally thought to be too small for a 400cuin engine, so most folks removed it, permitting road dust from the front tire to be drawn in thru the various cracks and openings in the fender assembly.
OK, JD, I'm gonna call you on this one. I (still) own a '93. The snorkel was partly to blame for the debris sucked into the air filter. The snorkle inlet was right next to a small hole between the inner and outer fenders, near the bumper tip. The suction from the snorkle pulled the debris in through the hole. GM identified the problem and fixed it in later models, buy covering the hole with rubbery material, and issued a service bulletin for the earlier trucks. Later still (around the introduction of the '95 model year)an additional issue was identified. The snorkle could become clogged with snow and ice resulting in reduced performance or complete engine stoppage. The snorkle was eliminated from production at that point.

Removal of the snorkle merely brings the earlier trucks up to later production standards.

I think the ram air effect was minimal at best. The air entered the system from behind the headlight and was ducted around a couple of corners into the fender. The connection from this duct to the snorkle was by proximity only, and wouldn't transmit any pressure to speak of. the injestion of debris further indicates that the snorkle was under negative pressure, not positive pressure.

Happy New Year,

[gmctd]

I may have to eat crow on this one, John.

The late '94 K donor of my engine had a corresponding duct fitted into a 2" by 5" (iirc) opening at the front bulkhead, down low, below the battery level. It fit into the snorkle opening, again iirc. I had the complete, bent fender off the donor truck, which I cut apart to get the ducting and pattern.

While I seldom see snow and slush, TV and pictures look like that would be a problem in those areas.

Recognizing the ram-air benefits of that system, though, properly plumbed, I tried to plumb it into my truck. Just didn't want to cut and reweld the inside fender panel.
And, the 6.5 air box occupied the real estate required for the original coolant reservoir.

I've rethunk it for a front bulkhead-mounted housing, ported thru the radiator support like the original 6.2 config.

Hmmm...wonder if crow works with black-eyed peas, brockley, and corn-on-the-cob? ;)