'72 280SE 4.5 hot starts, fuel filter, misc. questions

[kpb]

I posted a thread a while back asking about my "crappy idle in rain." Received a few ideas but now, with more time (22 days ) with the car I have found a pattern. Starting while warm results in a stumbling idle (when the fast idle is not kicking in any longer) but driving and idling at stops is very smooth. It is only the initial warm starts which are rough and require finessing the throttle to get under way. Is this a vacuum issue? Otherwise, the car runs smooth and fast.

I have a fuel filter and ran a bottle of Techron through the system. Are there any unusual quirks to replacing the fuel filter? I do have the shop manual CD. It has not impressed me thus far and I do not care for the organization were one cannot view all the contents at once.

I also have fresh oil pan, tranny pan, and valve cover gaskets since I have a few leaks. Any oddities or known troublesome areas when renewing these gaskets? I do not want to start an ostensibly simply project only to break rubber or plastic parts nearby and need to turn it into a major event.

Finally, I have looked at all of the info I could find on the subframe mounts, including the DIY by Mike Tangas. This looks do-able but I am wondering as to the necessity. Is there a way to check the integrity of the mounts? Of course, the car is 32 yrs. old so I guess the rubber should be presumed shot, but the handling seems crisp, no wander under braking, nor any unusual noises or feels -- odometer just turned 44.2K, from the looks of the body, mechanicals, and interior, I believe it.

As always, responses gratefully accepted...

[Tomguy]

A great way of telling if the subframe mounts are REALLY shot (like mine are):
If you jack up the front end by the frame so that both front wheels are off the ground (car is 100% supported by the frame up front) and you look under the hood at the mounts (you will need to take the battery out to see the right side) and see any light coming in from around them, they're gone. You need new ones. My car handles very well but does undoubtedly "Float" over some corners/road conditions where going up a short incline and then going down one (the main one I can think of is the Scranton Expressway in my area, right after the Main Ave exit... PaulC would probably be the only one who knows this one...)

As for the fuel filter, the pump and filter are together on a bracket that's attatched to the body in front of the fuel tank (and in a little "cubby-hole"). You may have to take it off the mounts (I don't know, my mounts dryrotted apart long long ago) to access the filter, but it's pretty damn easy - take the lines off, loosen the clamp (machine screw), take the filter out. Installation is reverse, naturally. A 10 year old with a broken hand could do it (Especially if *hint* you drive the rear up onto ramps or jack it up (SECURELY!)).

The other seals, although I haven't done them, look pretty straightforward (I WANT to do them sometime soon - mainly the oil pan seal). I don't know how hard it would be to do the oil pan seal though without jacking the front up by the frame (and still I don't know about ease, I'm afraid of the subframe being in the way - you'd have to ask one of the guys here who have done it).

As for the idle issue, it sounds like an issue with your throttle position sensor not picking up the closed condition at idle, and the idle has been adjusted for this. If you fix the switch it may idle worse, but when you fix it it might help. Otherwise, I'm as clueless as you on it (but that's where I'd first look!)

[psfred]

Have you cleaned the trigger points in the base of the distributor? This is the weakest point of the D-Jet, they get oily. You have low milage, but the seal IS pretty old now...

Front subframe check is easy -- look behind the shock at the "cup" on the subframe where it "meets" the body frame. If you cannot see the rubber mount in there, it's squashed. You can also check the upper mounting under the hood -- the large bolt and washer should be an inch or more down inside the oval stamping and centered. If it moves around (ie it's offset to idfferent locations every time you look at it aftrer driving), the mounts are too soft.

My 280 rides pretty high in the back, but has a trailer hitch and aftermarket shocks -- Monroes, I think (medium blue, definitely NOT Bilsteins) -- if they are 'load levelers' they are forcing the rear up. I've got some used Bilsteins (don't laugh) off eBay to put in this week, may bring it back down. Causes the rear to move more than I like at speed on curves.

Peter

[kpb]

peter -- thanx for the insights. I have already studied my subframe mounts and cannot see them behind the shocks. Think I'll put this off til spring since everyhting around here is a pit of mud at the moment. My ride seems to be a bit low in front and I guess that is due to the sqyashed mounts, although the handling seems great.

Will check my trigger points soon. Hope I do not screw anything up by diggin around when there may not be anything seriously amiss...

kpb

[WANT '71 280SEL]

Think that's bad Peter! I am currently looking for used engikne shocks for an 617 turbodiesel. I have only seen on\e auction which was only 20 miles north of my house, but those were from w123 and don't fit w116. Well, I know I'm not the only one who tries to save every penney possible.
David

[Tomguy]

There's nothing wrong with saving a few bucks - Hell, I bought used cams to replace my (badly worn) cams. Even though they were the lower-power ones I didn't care - I am 500% sure I get more power/better running with these than the ones I had on with flat lobes! (I was told they were from a 74 450SEL, and the PN is different)

Now, if you want to know... I paid $90 for the pair, with shipping!