Hi, I have an oppertunity to purchace a 420 sel at a great price from a dealers lot.
However the car is not running at this moment. When the dealer got the car all the spark plugs were taken out and he hasn't time to replace them and check out the car so my price is as is. or I can purchace this car fixed at a higher cost.
Now before I purchace this I would like to check the compression (maybe thats why the plugs are gone) can I get accurate compression reading with all the plugs out? or do i have to put 7 of them in?
also I've read about people using starter fluid on these cars.. how do you do that with a fuel injector? I know carbourated models just take a quick hit in the carbs chamber...
everything else visually looks great new brakes, tires exaust, suspension.148K orig miles, inside's nice just a few normal wear and tear front seat cracks.
so any ideas?
thanks, Jeff

Jeff, unless it is really cheap walk away, there is a reason the plugs are out. The timing chain could have failed and buried the valves in the pistons. If it runs thats one thing, why would a dealer have car in that condition and why have they not screwed plugs into it and tried to fire it. Dealers are not dumb just crafty, at 148K it could be anything.
BTW: compression tests are usually done with all plugs out, if the fuel system works it will pressurize the fuel rail at startup. The trick of spraying ether went out many years ago and has caused some engine explosions.

Walk away and never look back, the dude above me is completely right, I agree with him 100%...

Dealers have access to spark plugs all the time, such B.S. that they say they don't have time... they be trying to burn you man!

I know it must but tempting, but you may regret it!

Anyways, if you think I am full of B.S. and just jealous of your find...

Go ahead and do the test, you may get very lucky and have your self a nice new car!

As for the spark plug question.. .it makes sense to me that you could leave all the spark plug slots empty since they are indepenent of each other... when testing for compression.

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2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)

thanks, I'll still go and look at it. not having the car fixed was my idea. he's one of these back hill town dealers, auctions and trade-ins that type of thing. only open 3 days a week cause he has a normal job too. I kinda figure I'll just drop in some plugs and see if she fires up. if so great, if not no lost.
hell gas is too expensive to really drive that gas hog anyways
I just hate to pass up what might become a golden opertunity.
J

Bosch plugs are about $1 each for that car. Why are the plugs out in the first place? Something is not right.

Anyway as with any M116 make sure the chain has been done. At 148k if it hasn't it probably broke.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Use this as an opportunity. When you said great price, you didn't say what.

Offer the guy $200.00 or $300.00 as is. If the rest is O.K. you can always part it out for a real profit. Or? Have you ever had a total engine rebuild project? Everyone should do at least one!

Have you dipped anything into the spark plug holes to see if any water or anything else comes out. May have been this way for a while and could be very bad in there on one or two. If the other suggestions were not the problem, I would suspect blown head gasket reason for the plugs out and then abandonment mid stream. No one would push this thing around auction and dealer lots by hand when $10.00 would make it run.

But go with plugs in hand. Run a compression test, that’s real easy with a second person to turn the key. If you find a problem, only buy if you want to part it out. There are a lot of nice MB's for $3000.00 or so out there in great condition. Replacing that motor or major parts will easily put you in that neighborhood.

If you just put plugs in and start it and it's total bad news the dealer may accuse you of cross wiring the plugs and breaking his pride and joy. Then demand big money for his broken car, use caution! Get things in writing like waivers of liability? or at least photo's and a reliable witness prior to doing anything? Never trust a car dealer that is not married into the family! You sort of got to work with the latter until the divorce.

Scott

I guess I'll just forget about it looking through this web site this car seems like the worst thing benz ever came up with. no one has anything nice to say about them. as for a great price i was offered $450 as is or $1200 up and running.

I placed the plugs in the car and no go. engine turns over very smooth very quiet. everything looks good however I probably did the plug wiring wrong. i cant find any info on the cylinder order. the way the wires in the harness were setup it went in normal counting order pass side 1234 drivers 5678 now i know that cant be correct. I've never seen a car that would be set up like that normally its something weird like 1352 7684 i dunno, the firing order don't help unless you know which cylinder is which. It also seems like theres a lack of fuel going to the engine I pushed down on the air vent on the injector and the smell of gas was pretty weak it eventually got stronger but i had to go to work by that time.

I dont belive the head gasket is blown coolent looks fine oil looks fine no muddy appearence. theres no noise coming from the timing chain area no knocking from the cam areas either. everything seems very clean and smooth.I bet it something very simple that just being over looked

Firing order should be 1-5-4-8-6-3-7-2. Check the Owner's Manual to confirm. Your identification of the cylinders seems correct ... 1 thru 4 on the passenger side and 5 thru 8 on the driver's side ... counting front to back.

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Fred Hoelzle