Experts weigh in, please; '91 420SEL
 

I am to look at a 1991 420SEL, on Monday. It is a one-owner, Arizona car with 109K miles. Dealer claims to have all service records with the vehicle.

I intend to try to purchase for somewhere in the $6-6500 range. I need a quick course in this model Benz with as much good, bad, and ugly as you feel like providing. Previous or current owners, techs, please help me in this.

TIA

Never owned one and don't know them that well, but I seem to recall that there are plastic oiler tubes that deteriorate and must be replaced or you're looking at damaged camshafts. I understand that it is a very cheap and easy fix and ought to be a routine maintenance item. Maybe others with more info can chime in on this one.

Len

If I were you, I'd hold out and find a 560SEL. One can be bought at the same price range.

I'm pretty sure the "oiler tubes" affect M119 engines only, not the one in the 420 or 560 SEL.

Why snibble?
Something wrong with the 420SEL? They look identical to me, except for the 5.2 liter in yours?

I would take the 420 over a 560 any day, the difference in power is not that much. Plus you don't have to deal with the possible problems with with rear hyd shocks. These were a hard ride from the factory, and expensive to fix if there is a problem.

On a 420 you can just change the shocks for a part cost of less than $200. for OEM shocks.

They need the timing chain and rails done every 100k like clock work. Don't try and put this off on a M116 or you will be looking for a new engine.

If no record of them being changed comes with the car plan on spending $500-$1k right off the bat.

Other then that basic W126 problems that have been talked about to death. Rust shouldn't be an issue with an AZ car.

Only the outside is same.

Inside and under the hood its different. The 560 came with all the luxury options and had burlwood as opposed to zebrano. The engines on the 560 are a little more lineant on timing chain tensioners breaking than the 420. Oh and the 560 has a 5.6L not 5.2.

Not yet convinced
 

Hatterasguy says: "They need the timing chain and rails done every 100k like clock work. Don't try and put this off on a M116 or you will be looking for a new engine."

I've read a few hundred posts re timing chains, and I am under the impression that the 420 has an M117 engine. This timing chain issue reminds me of the many "oil change" threads; not much agreement to be found.

Does the M117 engine have the double chain? Is it the chain, the rails, or the tensioner that should be the more-closely monitored? Obviously, if I'm to go with the aforementioned vehicle, I'll go through all the records, and just as obviously, will not want to take any chances for a TC failure, but don't want to spend unnecessary money, either.

One thread I read through suggested to line up TDC on #1 cylinder, and check to see if the cam tower mark lines up with the mark on the gear as a way to check stretch. Theory being that no stretch meant no problem with the TC. Later in the same thread, it was suggested these double-row (if that is what the M117 has) are virtually bulletproof from the factory, and that the tensioners were all that needed to be replaced at the 100k interval.

Where is Larry Bible when I need him?

Thanks for all the commentary, and please keep it coming.

While I'm at it, what kind of fuel consumption am I to expect on the 420SEL?

i have a 90 350 sdl. aside from the head gasket issues i have had and related engine stuff, the rest of the car has been excellent. it had 132k when i bought it and has 150k on it now. the interior and all the related hardware work just fine. i recently had a loose wire on my blower motor which was easily fixed. and some speakers arent working but other than that everything is working excellently.

these 126s are a fine ride. and lots simpler than the cars that followed. also without the leveling suspension in my book a plus. its nice but for the cost of maintenance i will pass if poss.

the front ends usually need some bushings around 100k to 120k. and you will want to do shocks soon if they are orig.

i dont know about the price. it seems a little high but it is at a dealer and they need to make some to stay in business. i would try to get them to fix a few things prob.

tom w

http://www.mbworld.org/forums/showthread.php?t=140755

The 420SEL has the M116. Its your car, ask any tech on this site. You leave the original chain in these engines past the 100k mark at your own risk.

M117's you can get away without changing it for longer.

On my 4.5, I changed my chain at ~140k miles. It had a massive 12° of stretch, but no interference between the valves and pistons occured. I don't know if the 5.0 and 5.6 M117's are this way, but it's very possibly because the pistons on a 4.5 don't go all the way to the top of the block - they do on a 3.5 M116, and I am pretty sure they do on a 3.8 and 4.2 M116 as well. Timing chain stretch on these is more likely to cause the valves to kiss the pistons. See the link in Hatt's thread? Looks like an M117...

I saw a nice 420SEL in the junkyard. Well, it would have been nice had the owner replaced the guide rails. I saw 175k on the odometer. I grabbed the starter from it, and the valve covers were already off showing the valvetrain someone probably wanted. Several bent valves on the right side of the engine (didn't check the left). It was saddening how a $25 job (in parts) cost this car its life.

I almost bought an 87 420 for $2500. It was immaculate, 120k miles. And I mean IMMACULATE. Someone else got to it before me and offered $3k. I was going to offer back with $3k but it was gone. 420s are pretty low demand, people prefer the more powerful 560 with its nicer trim (IMO). Price is a bit high, you can get a perfect 560 for that.

Go for 560SEL or at least 500SEL which are more powerful than the 420SEL.:rolleyes:

No offense
 

I did not intend to call anyone's knowledge into question. My mistake. I have read so many threads regarding these vehicles, in the past two days, that I was just confused. The last thing I want to be accountable for is a "Mad" Hatterasguy.

If this car is what it is being touted, the PO would certainly have taken care of the timing belt. An acquaintence of mine has the car on his lot; says he flew to Phoenix to pick it up, and it has all MB dealer service records. The timing chain history will be the first thing I will look for.

The Indy that I have always used for my SD is just across the river, in West Memphis. I have an early afternoon appointment for him to check out the car. I would not purchase without his okay, and the price will have to be moderated if the TC has any issues.

Still very appreciative of all the comments, and welcome any other hints or advice.

It's not so much the chain, as it is the rails. With age and heat and whatever other things in their surroundings they are assaulted by, they simply get brittle. One day, the chain slaps up against it a little too hard (usually at start up - there are no other symptoms, unless you can identify the sound of chainslap).

Most folks, when they replace the guides, replace the chain at the same time - might as well, since you are already in there. In my case, on my 420, it was discovered that I had bad lifters and that the cam was on it's last leg. Rumor has it, that those 2 items are not all that unheard of.

Personally, although I liked the ride and most other things about the 126, I do prefer my 124 (E420). Not only is it a good bit shorter, but it has less body roll, is shorter and lenght, has 74 more HP and gets 23-24mpg (vs. 17ish in the 126).