Mike J

Hmm, not sure if I agree, because:

- After nine years of ownership I have no scrapes on the heat exchanges, and my car is LOW
- The tray sits below the engine, and would likely take more scrapes than the engine itself would, so I suspect while I do not scrape without a tray, I would with one.
- When the tray scrapes, it deforms and likely bangs against the engine...not sure if I like all that plastic touching some high temperature components.

Cheers,

Mike

goofballdeluxe

When I was running without an engine tray, I had a heater flapper box get caught and ripped off when I backed out of a driveway. My car is lowered as well. I am also not the only person this has happened to. This would not have happened if the engine tray were left on.

Of course, just because it happened to me, and others, doesn't mean it will happen to you. On the same token, just because it hasn't happened to you , doesn't mean it could not.

As I said earlier, there is lots of theory and conjecture regarding engine tray and heat, etc. and whether one should run with it off/on.

This is at least something concrete and tangible that proves a real, and potentially expensive, downside to running without an engine tray. I'd love to hear something concrete and tangible that proves the advantage that comes without running one. So far, I've heard lots of ideas, but no proof. This is proof of a downside to running without an engine tray.

So, to my simple brain, we have proven downsides but no proven upsides, so I'm keeping mine on

Mike J

I suspect your heater flapper box was not positioned correctly, mine do not hang below the centerline of the engine...so it could be that people who remove or adjust them are just not putting them back right?

So it could have happened to you and others just because your flappers were not set high enough...same counter argument.

My sample size is 9 years of ownership with the 993 and another 9 years with other 911's, making 18 years of driving these cars, i have not once had an issue with engine scraping. And oh, I have had my tray off all that time, and in fact it was tossed into the garbage about 9 years ago.

Also remember when selling your car, if you tell the buyer your engine tray has always been on, especially in the LA heat, I bet that will make it more difficult to sell (regardless of the eventual outcome).

Cheers

Mike

goofballdeluxe

I suppose it's possible my heater box was positioned incorrectly, but I imagine it was in the position it was set when it left the factory, as I never adjusted it or touched it at all. So, it could be possible that like mine, others were set incorrectly, and the removal of the engine tray could expose them to the road surface if the car were lowered and one was, say, backing out of a driveway. I'm not talking about the engine scraping, just the heater box.

Yes, I know you are very knowledgeable about 911s, more so than I for sure, but I just wanted to point out this is real proven downside that some owners have faced, that's all.

I doubt I'd ever have trouble selling my pristine C4S regardless of whether I had the tray on or not, but I'll keep your suggestion under advisement

Dudley

A lot of new owners will follow the lead of the more experienced fellows on the board. The problem is that these new owners bought cars that may not have all the maintenance required. The inexperienced owner will not recognize the potential risk of a suggestion made here.

The engine cover is a case in point. With out the use of a jack, a fellow can reach under the car and loosen five fasteners to remove the engine tray. Did he verify the postion of the heater boxes? Who changed the oil last? During the oil change, did the intern at the dealership over tighen the hose clamps and cut through the hose? Did he check the condition of the orange heater hoses? When the heater hoses age, the rubber deteriorates and weakens allowing the boxes to droop. This will not happen to Mike or Robin or Steve because they know these cars, but the newbie?

I took my engine tray off at the track, otherwise I left it in place.

Oh, I almost forgot. I bought my repacement heater box at DC Automotive, the orange heater hose and oil return tube at Sunset Porsche. (When I caught my heater box at the edge of my driveway, it was driven up into the engine and crushed one of the oil return tubes.)

goofballdeluxe

Well said, Dudley. So besides the cost of the heater box, there is also the cost to replace your oil return tube. And as we all know, Porsche parts aren't cheap. I was able to buy a used heater box from a fellow RLer, but new they are a few hundred, and add the cost of your new oil return tube and labor and it's a pretty expensive experience.

I may not know much about Porsche's, but at least we have solid proof as to a potential major downside to running without an engine tray. Still, no one has given me any solid proof as to any advantages to running without one...

niche

As far as I understand, heat RISES... so how much additonal cooling can you get from removing the tray, anyway?

Sam N

The debate still goes on? Back when I joined it was being analyzed and discussed.

goofballdeluxe

I would say the debate is over, now that we have solid proof one way or the other.

There's no proof of any advantage to running without an engine tray. There's solid proof that running without one, especially on a car that has been lowered, can result in expensive damage to one's heater boxes and oil return tubes should the heater boxes droop.

This cannot happen with the engine tray on.

The debate, and my contribution to this thread, is over.

Merry Christmas, all!

kilodawg

Absence of evidence is not evidence of absence.......

I live in Florida, the roads are flat I'm careful with any driveways that are steep so to me physical protection is a non-issue. However the heat is something we deal with 7 months out of the year.

cgfen

sweet
i'll look forward to seeing your results.
make sure all your cal cert's are available for inspection


Craig

arjag

Proof: several members have reported damage to cars without the undertray
Speculation: undertray may cause overheating...

Until we hear otherwise the tray stays on. Speculation just doesn't cut it in a finely engineered German automobile!

IXLR8

Looking forward to my results? Hey, I'm doing this to satisfy my own curiosity.

No need to worry about the measurements...I've been working in a standards lab far too long.