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Discussion Starter #1
i'm looking at an 84 500 SEL that has been overheated and sitting for the past 4 years or so. the owner doesnt know how to work on them so he's letting it go. i understand the 5.0 is all aluminum and i'm wondering what effect, if any, the overheating may have had on the block. i'm planning on having the heads straightened and resurfaced because they never survive that sort of thing, but if the block is bad, i'm out. i'm also concerned about water having gotten into the cylinders and, having been sitting for so long, the rings are corroded into the cylinder walls. i've seen this on iron blocks, but i've never worked on an aluminum block. this is also a Euro spec car, supposedly, and idk how difficult it would be to find an economically priced replacement.

any personal experience with any of this is much appreciated.

thanks
jason
 

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W123 Moderator
78 450 SL, 84 500sec (Euro), 94 E320 Wagon and 85 500 SEL (Real AMG, 5.4, Pentas & Body Kit)
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797 Posts
Get a junkyard engine

I have experienced this a couple of times.

Every time I fixed it with a different engine.

The first one did a head gasket and the cheapest way was to replace the engine with another one, engine cost between $100 and $200 bucks.

The next one, I broke the radiator and almost ran out of water, after six months of trying to make it run right and not boil over, I replaced the engine with another one. Again approx cost $150, the replacement had just been completely gone through so had a valve job new rails and new rail etc.

The only engine that I had rebuilt was my AMG. The engine had a head gasket problem and had been overheated before, this time I spent approx $5000 on having the engine completely gone through, due to the fact that the heads had been machine too low the shop recreated the AMG heads from a standard set and did a complete rebuild and sent me back a brand new engine.

So there you have it.

Replace engine $200 plus parts for rails and chain etc.

Rebuild engine completely $5000.

I hope this helps.

Jonathan
 

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1988-300SEL 1989-300SE
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are you getting it cheap?? several hundred bucks? what is your intention with the car...to drive it or resell it? lots of variables.

i would negotiate a price as low as you can depending on if the car cranks. then pull the plugs and try to see if the engine is spinning and if any water is in the cylinders. you can pour some marvel mystery oil in the cylinders and let it sit for a few days to make sure the rings arent seized. i like to change the oil in cars that have been sitting for a long time. clean the plugs. siphon out the old fuel thats in the tank. hope that the fuel tank and fuel lines are not corroded. put in clean fuel. see if you have spark at the plugs. if it wont crank, spray in some starter fluid. if it fires but wont stay running, at least you know the engine might run and not need all that work you are talking about.

find out from the owner what condition the car was in when he parked it. was he running it overheating, or did it over heat and he parked it? how long did it overheat...what were the conditions?

if you are going to flip it, then you dont want to put much in it. if you are going to keep it, then thats a different scenario.

first thing though is to get into the car for only a few hundred bucks...i like to use salvage/scrap value. if you can get $500 at the scrap yard for it, then dont pay more than that for it. parting out a car to recover your investment is a PIA! good luck!!
 

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2012 CL550 4MATIC Coupe
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Overheating is bad... Very bad....

The block is bulletproof. It's the heads and head gaskets that don't survive well. If your intention is to rebuild the motor, then okay. But severe overheating is usually a death sentence for these motors. The top end anyways.

This is what happened to my car, and also Cascade's car too.
 

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Discussion Starter #6
thanks for all the great feedback!

so, i guess my intentions with the car will be to fix it as inexpensively as possible and enjoy it for a while. i am currently working on bartering for the car and the total value will be around $500 or so. the owner wants $1500 in value because he has some nicer rims and low mileage tires on them (even though after 4 years they are dry rotted and basically useless/dangerous) but he'll keep the rims/tires and let it go for $500. he can have them.

i dont have the time or money to restore it right off, but depending on how it goes with the engine i'll likely make improvements as i go. i've always gotten the impression that aluminum blocks are pretty resilient to heat, as an iron block is. that is what i was hoping to learn about these engines. so, it sounds like i should be able to use this block, re-work the heads and go from there. i saw an engine on ebay (i know, right) for $700 and didnt want to put even that much into it right away. but, 100-200 doesnt sound bad, i'll keep my ear to the ground for one. but, again, i'd rather keep it to in-chassis work, if i can.



also, i'll need some cheap steel rims to get it home. are most MB wheels interchangeable with regard to bolt pattern?

thanks again, guys. i like this place already. a lot of forums leave much to be desired with regard to specific technical advice.
 

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2012 CL550 4MATIC Coupe
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Well I can only tell you what happened to mine, and it appears the head gaskets are fragile when overheated.

Here are my two observations:

First with my own car: Before my engine blew the car was idling and sitting there and it overheated up over the 120 mark for about 5 minutes until it was boiling over. I was standing next to her as she idled talking to someone and didn't notice right away. The car "Heat Stroked" as I call it and about 6-8 weeks later is when the HG blew, then the chain guide went too... I had just had the guides inspected and Alfred said they were okay. At the time of the blow, I had noticed that it was badly overheating, and then the chain went "Pop! Crunch! Gurgle, gurgle...". IDK which went first, the HG or the chain guide. Maybe both? Maybe neither.

In the second case I will cite is Cascades car. It is well known that he and Chadahar were driving up north, had a problem with the power steering pump. So they pulled over and cut the two main drive belts, which also drive the water pump. They continued to drive and the car overheated. "Heat Stroked" I felt. Although they said they did not drive that long, or far, or at too high a temperature, I felt at the time his motor was doomed.

At the time it happened and when I read the post, I was talking to Bondavi about this and I told him right when it happened that Jim's motor was "Dead Motor Running" and would probably be toast within 6-8 weeks like mine was.

Sure enough, about 6-8 weeks later, his motor finally gave out and Bondavi said "How did I know?" I recalled the events leading up to my motor's demise, and he agreed that that could very well be the cause of Jim's motor giving up the ghost. Jim's motor was in MUCH better shape than mine as everyone knows how well he takes care of his cars. My motor had a buck 87 on it and I believe Jim's was in the 160 range. He had done his chain guides, where I had not. He had his car and motor since nearly new, knew all of the history on it, and maintained it meticulously all it's mechanical life. My car and motor was 6 minutes away from the scrap heap, with an unknown history and judging by it's condition, was rarely, if ever, taken care of.

And that's why I drew that conclusion, because of the different care histories of the two cars, but with the same overheating type incident, then both motors going out in the same type of time frame.

Note to Jim: Jim, I am not trying to stir up anything with you, just drawing a corollary between the two motors as to why they blew up after overheating. You can talk to David, what I said was true. I truly feel that that type of critical overheating spells Death Nell for a M117 motor, or any motor really. So please don't take it as a poke and start raising hell here. It's just a technical analysis of why our motors blew after the exact same incident, after the same amount of time.
 

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Discussion Starter #8
i forgot to detail how this car got hot. he said that the water pump was leaking and getting worse, rather quickly over just a few days. so, he attempted to drive it about 20 miles or so to his mechanic. well, on the way it boiled over twice and he had to add water both times and when i asked how hot it got his response was, "pretty hot". his mechanic proceeded to change the water pump and when they started it up it "started to smoke really badly". now, i dont know if that was steam, or oil burning, or even if it was out the tailpipe or around the engine, but he then shut it off and towed it home where it has been sitting ever since.

anyway, it sounds like this car is not going to cost me an arm and a leg and its not a complete basket case, so i'm going to try to make a deal with the guy. even if it starts to get too hard on my wallet, i can always let it go for scrap.

wish me luck!
 

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I think an overheated motor would have very bad effects on critical plastic items even before any warping takes place (oil tube fittings, guides, and consider that there are guides that you can't see, including one for the oil pump chain).
 

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2012 CL550 4MATIC Coupe
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I think an overheated motor would have very bad effects on critical plastic items even before any warping takes place (oil tube fittings, guides, and consider that there are guides that you can't see, including one for the oil pump chain).
Yes, agreed. That is what I thought too. The heat stroking of the motor caused the old, brittle plastic guides to accelerate in their wear and break, thereby causing the chain to jump, and the resultant valve damage.

To the OP: You should fill out your profile so we know where you are. As Jonathon pointed out, yes, you can get motors here in California out of the junk yards very cheap. I replaced a tranny for $90.00 and it runs great still. But if you are located in BFE somewhere, then a motor can and probably will, cost you more than a couple of hundred to replace, and certainly repair.
 

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Knowing what I know now id replace the engine and never bother with doing the heads. Your never going to get what you had before it was cooked.

Reuben
 
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