I took my flame arrestor off my 2000 Merc 5.7L EFI some time ago to clean it and just got around to putting it back on. One problem, I seem to have a fitting with no hose to go on it.

I reattached one electrical plug, one small rubber hose not visible in the pics and the one corrugated plastic hose in the left rear seen in the pics. I cannot find anything loose to go over that right front fitting. Is it left open? Can anyone figure out what the deal is? I've done this numerous times before and don't recall any issues reconnecting, but I've never had the time lag I had this time.

It's possible nothing was hooked up to it, but that it is there for use on different applications.

athiker
That fitting is used reburn fumes from the crankcase. Usually it is hooked up to a rubber hose which runs to a fitting on the valve cover.

I can barely see a PCV valve in your left valve cover, at the front. If you back up and retake a picture, you'll see where that tube goes. Regardless of where it is now, the tube from your left side PCV valve is supposed to be attached to that fitting on the spark arrestor.

Wait, I see your PCV valve hose goes to the front of the Throttle Body. And is a firm rubber hose, not corrugated like the right side hose. If that rubber hose has always gone to the throttle body, then that's the way it's supposed to be. That fitting is just extra, they didn't change the arrestor, even though they changed the location of the PCV hose. Those arrestors have looked like that for a long tme, and fit several different applications.

Thanks guys, yes my PCV valve is definitely connected w/ a solid rubber hose. It can barely be seen in the lower right corner of the 2nd photo and the hose does appear to run to the front of the throttle body as BillyB mentioned...though I can't check the connection point right now. I do know I checked the PCV hose and it was connected somewhere. By location it makes sense that this PCV hose could have run to the flame arrestor in past configurations.

The area is pretty open so I was really stumped when I couldn't find a hose to attach. Guess I should have take a picture BEFORE disconnecting! I'll rest easier now...thanks.

that's something i started doing a while ago and found to be very helpful. it doesn't even need to be high quality pictures. the camera on most phones will do a good enough job to get physical or electrical connections back together correctly. the only down side is when i'm showing people pics of my kids on my blackberry and they say something like, "what's THAT a picture of?" i tell them it's a rotator cuff raw water plenum regulator and ask why they don't carry pictures of theirs around as well.

What's the sensor at 7 o clock on the arrestor? An air temp sensor?

Don't know, but would like to. Unfortunately, I have no one availible locally to ask these kind of questions; I just try to concentrate on putting things back the way I found them...and sometimes fail at that!

Here are a couple full engine shots w/ and w/o the arrestor in place:

I'll look at my 1997 TBI 5.7 tomorrow and see what hoses I have. I am thinking that the hose from my left valve cover goes to the arrestor, not the front of the throttle body like yours does.

Wait I don't have to. You can clearly tell in this photo that my hose from my "PCV valve" on the left cover is going to the arrestor where yours has nothing hooked. I'll look tomorrow and see what's at the very front of my throttle body, where your hose is. I am gonna bet mine has a plug in there.

Thanks Billy I think you are exactly right. They must have decided it was better to put it back lower in the TBI throat as it were vs. the flame arrestor at some point between '97 and '00. I took her out Sat & Sun and she ran great.

Glad to hear it. I forgot to photo mine yesterday or the day before!

Good one. ha ha ha