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Replace engine or headgasket

  • Drop the head at the machinist, hope for the best and attempt replacing myself

    Votes: 1 7.7%
  • For $550 I can get a tested salvage engine locally with 65k

    Votes: 6 46.2%
  • For $1200 I can get a tested salvage engine and supercharger locally with 55k

    Votes: 6 46.2%
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Discussion Starter · #1 ·
Hello all, I purchased a 1999 SLK that has been overheated and most likely has a blown head-gasket(or worse) due to milky oil. It would run when purchased, but very poorly. Now I am trying to decide what to do as I have taken the head off.
I am a little worried about the procedure to correctly reset the timing and am worried i will do more damage if I was to attempt replacing myself. So I wanted to get the forums thoughts on my current options.
1)Drop the head at the machinist, hope for the best and attempt replacing myself.
2) for $550 I can get a tested salvage engine locally with 65k
3) for $1200 I can get a tested salvage engine and supercharger locally with 55k


Current mileage is 115k
What would you do? And other suggestions are certainly welcome
Thanks
Scott
 

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I made you a poll :D :D
 

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2005 SLK55 AMG
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He's had practice!!

Who's doing the engine swap if you go that way .?

Only asking as setting the timing up should be easier than a complete engine swap ....
 
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Having looked at the proceedure to replace the head gasket it seems to be a long job with many special tools needed. Not easy ! Two points to make. If the overheating was severe the engine may already be ruined so replacing the head gasket would not fix the problem. Also why was the car overheating ? Has the cause been identified ie radiator, hoses general neglect etc. I would replace the engine with a secondhand one and keep the old engine. Maybe at a later stage if prices were to rise it may be economic to rebuild the old one to keep the numbers matching.
 

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Replace engine or headgaskets?

Isnt it a horrible question when you have an issue and want to decide what to do for the best? Back in the days (20 yrs ago) when I had a ford 2.8 Capri and an Austin Mini (must be 15 years ago), I changed the heard gaskets when I had had a head gasket diagnosis. These days however, motors are somewhat different. My parents mechanic was recently saying that many heads need to be skimmed when you are fitting a new head gasket... I wouldn't like to be in your position, but depending on how long you had overheating issues and if you have done a few miles maybe at higher speeds/temps? I would be inclined maybe to try and sourse a low mileage engine and have that fitted as you don't know what problems your overheating may have caused? I think that the 2.3 might run hot anyway eh? In two years ownership, I have noticed that after a drive the bonnet and engine do seem pretty hot, without any problems or temp warnings showing, but I think it may be an engine that runs fairly hot. Maybe many mercs do. Hope you can sourse a low mileage engine and get it fitted. Hope you get it all sorted. :( kevin


Current mileage is 115k
What would you do? And other suggestions are certainly welcome
Thanks
Scott[/QUOTE]
 

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Remove the head and inspect first!

Save yourself some money (initially) and learn a new skill. I just replaced my HG. I had the dreaded coolant leak at the back of head at the firewall. The engine did not overheat and there was no coolant in the oil (65K miles). I believe the coolant had never been serviced in the past. Not only was the HG replaced, but also the timing chain tensioner, water pump, thermostat, intake and exhaust gasket, supercharger gaskets, exhaust down pipe hardware, hoses, tensioners and pulleys, belts, vacuum lines and some hardware. For the most part a bottom and top end freshening up. The only two specialty tools I required was the socket for head bolt removal and the chain guide pin removal tool.

Ben Kokes has a very good pictorial that will give you a good start. It won't cost you anything to remove the head, then you can inspect the valves, pistons, cam gears, timing chain, chain guides. All said and done, parts cost approximately $800.00 US and a good 20+ hours labor. I was also concerned about timing issues after the head installation. No worries, mark your chain and cam gear (intake and exhaust) at 20 degrees BTDC. This is also the position to insert pins in the intake and exhaust cam gears so as to remove the hardware (bolts) that hold them in place. The chain will stay positioned on the crankshaft, I kept tension on the chain using a bungee from the hood latch to the chain.

I decided not to resurface my head. After cleaning the deck and checking for it being "true" (straight edge and .0020 feeler gauge) there were no warp issues. I did not want to raise the compression by skimming the head. Your situation may be different based on the overheating issue.

Take your time, follow all the required torque values, clean as you go and learn a valuable skill. This is a very easy engine to work on. DO NOT substitute any other tool other than the one required to remove your head bolts and chain guide pin. Purchase the OEM or Victor-Reinz head gasket set and use quality parts, don't bother with cheap parts.

These engines are pretty bullet proof.
 

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Discussion Starter · #9 ·
Thanks to all who replied

A big thank you to everyone who replied! I have decided to take a combination approach to everyone's replies. I have decided to go with the low mileage engine replacement so I can get the car on the road and attempt to replace the head gasket on the old engine so I can learn a new skill. The engine swap will start this weekend. I will update when she is running again.
 

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Great! Closing the poll!
 

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Discussion Starter · #11 ·
A head gasket question

It really doesn't matter at this point, but when I took the head bolts out, the intake side were super tight(needed large breaker bar,) but the exhaust side were barely more than finger tight. For those with more knowledge than me, was this caused by the previous owner overheating the car? and would this indicate head damage?
Thanks
 

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2005 SLK55 AMG
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It really doesn't matter at this point, but when I took the head bolts out, the intake side were super tight(needed large breaker bar,) but the exhaust side were barely more than finger tight. For those with more knowledge than me, was this caused by the previous owner overheating the car? and would this indicate head damage?
Thanks

Quite probably .. and overheating tends to lead to head damage for sure
 

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I did a comp engine swap on my 03/230 model 121k to a 04 model 34k so a huge mileage difference.
Engine cost £450, & £500 to fit. Used my SC but had to fork out another £500 as it wouldn't work together.
Luckily i recovered £450 from ebay cos of the bad info on engine, but since then the car has ran superb. £950 all in for swap.
I now own an 03-37k mileage car which will do well for resale or mileage if i keep it for any length of time.

Oh, & i sold old engine (was the SC faulty) for £50 :frown:
 

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Discussion Starter · #14 ·
I am glad I decided to replace. Are there any DIY's that may be helpful? I have swapped several engines before so I am confident I can do it, but will also take any assistance :) I tried a search with no luck.
 

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