74 450 SEL W/117k - PeachParts Mercedes-Benz Forum

WINTS · #1 08-08-2006, 08:57 PM

Hi All,

I have been looking at a 74 450 SEL today with 117k on the clock. Same owner 7 years and regulary serviced.

Apart from a slipping fan belt, and the usual rust here and there, the major problem was that when flooring the gas, there was a rattling sound coming from the engine for quite a few seconds. The car was hot having been driven for 20 minutes in 90F weather.

The oil pressure was excellent and on normal acceleration no noise was heard.

Anyone have an opinion? The car has just had a recent $800 servicing/tune up/new tires. Asking price is roughly that!

Thanks.

kpb · #2 08-08-2006, 09:06 PM

Welcome WINTS. I am certainly no expert but, with the 4.5 in that car, I would look at the valve train adjustment. Sounds like a clattering from those babies may be the crux of the noise. IIRC, these are mechanical lifters, not self-adjusting hydraulics. For that price, I'd buy it even if it doesn't start

Tomguy · #3 08-08-2006, 09:39 PM

TIMING CHAIN STRETCH!

Sounds like a rail broke and the chain is very loose. Maybe a bad tensioner. Either way, it's not a major COST, but it's a major RISK to drive like that. If it sounded like a rapid "clacka" sound, it is almost definetly the timing chain. It could be as serious as a dead cam (or two dead cams). usually those are a lot more audible at idle though.

WINTS · #4 08-09-2006, 06:19 AM

Thank you all....

I thought it may be the timing chain issue. Tom, that rapid "clacka" sound describes it well. There is no audible "clack" on start up, idle, or normal acceleration, only when you push the pedal hard to the floor.

What's the average $$$ of getting this fixed?

Tomguy · #5 08-09-2006, 07:22 AM

The parts prices from FastLane:

Chain = $105.19
Tensioner = $193.97
Tensioner rail = $42.31
Smaller rail = $3.92
Larger rail = $4.80 (need 2)

Common quotes I hear are $500-700 which personally I think is high for a job I find easy to do.

Figure a MAX of 4 hours labor. I did it myself (never did it before) in 1 hour an 15 minutes for just the chain, including taking pics. To replace the rails, the alternator bracket must be removed and replaced (It'd take me 15 mins max), the power steering bracket removed and replaced (30 mins max), and then the rail pins pulled and rails removed/replaced (30 mins max). I could probably do the whole thing myself in 2.5 hours including the new tensioner. If I had a tool to roll the new chain in rather than using vise grips, the chain would take 45 mins TOPS.

WINTS · #6 08-10-2006, 08:54 PM

Thanks Tom...

I have decided to take the plunge for the grand total of...$750.

Driving tonight for 30 minutes with the sunroof open and the A/C cooling me nicely, all in relative silence convinced me. Seeing the recent bills for the new battery, fuel lines, ignition system, partial exhaust, all fluids serviced and 4 new Pirelli tires...well.....what can I say.....

I WILL get the chains looked at pronto...

Quick question~ What grade gas for this 74?

Thanks once again.

Andy.

Tomguy · #7 08-10-2006, 09:36 PM

You can TRY 87, but chances are (especially with a stretched chain) you'll ping on anything less than 91. I needed 92 in my 4.5 even before I put the higher compression heads on it. Some 4.5 owners have no problem on 87, others do - I suppose it varies with engine condition.