what do you guys think of the late 80's 5.6l MB engine?

[Ilike300sd]

Curious about this engine.  Is it pretty reliable?  How many miles would one expect with average but not stellar maintenance?  How does it compare to other non-6.9 engines such as the 4.5l in terms of reliability?

Thanks for sharing any thoughts and opinions!

[Big_Richard]

as with all alloy blocks, maintenance is even more so essential for the longevity of these engines, I would personally steer clear of a a vehicle with a questionable service history.  unless its irresistibly cheap and the engine runs smooth and pulls hard...

[WGB]

Needs good oil, regularly changed to protect that nikasil bore and has the same issues with timing chain and tensioner as the 4.5 litre motor.

More elecronic engine managment features may need more repairs.

Beware of a motor that has been stored in case any water gets in the bores and lifts the nikasil coating.

Beware of any engine that has ever overheated.

Other than that a fabulous engine.

Bill

[Ilike300sd]

This is very good info.!  Didn't know it had a nikasil engine.  I had a 95 BMW 740 with nikasil and never had an issue despite 150k miles.  The word on the street was that for US cars on that particular engine (don't know about the Jag or MB Nikasil engines) that it depended what part of the country you live in as there were large variances in the amount of sulphur in the gas.  I don't thnk it's ever been proven but from my very limited research the gas used did seem to influence nikasil deterioration.  I wonder if brand had as much to do with the area of the country in terms of Sulphur content. 

Oh well, those fuels are gone now as I understand it.  Did you guys have high Sulphur gas in Australia?  For a while I was paying attention to Jag XKs with the Nikasil engines.  Many of them never had an issue despite high mileage (these were all Pac. NW cars as i recall but that may be due to the fact that there are simply more local cars than ones from say the east coat or midwestern US).  Others had to be replaced quickly.  I think the sulphur content was a major reason and it's clear that sulphur content in gas varied.  Maybe it still does here. I don't know.

I totally agree with the comment about using good oil.  You really don't want to get me going talking about oil though... ha ha!

[jbrasile]

The M117 5.6 is an excellent engine, super reliable and durable. As mentioned before timing chain issues are basically the same as with 4.5's It is common to see 560's with over 250k miles and still going strong as long as the oil and coolant are changed regularly. I actually think that MB's first generation of all alloy engines is probably as long lasting as their cast iron V8's save for the problematic M116 3.8 US version with its infamous single row timing chain.

Having said that, I think fuel injection problems with the KE system are more common that with the older K-Jet and while delivering a super smooth idle and better fuel economy, KE's are prone to issues with the EHA, fuel distributor plate potentiometer, to name a few. Personally I prefer early M117 5.0's because they deliver more power and torque than 4.5's, are generally smoother and use the simpler K-Jet FI system.

Tks,

Joe

[TJ 450]

Ahh, there is no Nikasil coating in these engines to worry about. So, you won't have to worry about the issues that plagued the early BMW engines with Nikasil coated cylinders. The system Mercedes employs is entirely different, and is far more durable than even cast iron... As long as the engine is maintained properly.

The alloy contains a high silicon content. When it comes to treating the bores, a special lapping compound is used, which etches the once smooth surface, leaving the silicon structure exposed. This means that there is no actual alloy in contact with the piston rings, but rather the ultra hard silicon structure.

I think all the issues with these engines have been outlined in previous posts. I also concur that an early 500 would be better for reliability due to the fact that it uses the ubiquitous K-Jet setup. CIS-E or KE-Jetronic has a multitude of issues indeed, but it is more efficient as a positive.

Tim

[powerglide]

I have been told the same story that TJ relates. And this applies to all subsequent DB alloy blocks to date, I believe.  Same rule applies, as with cast iron:  Change the oil every 7-8000 kms, and change all the other fluids every 2 years.  Change ALL fluids, brake pads and all expendibles frequently, ie, before rather than after due, and all will be well.  And always watch the timing chain for wear/stretch.  This is the common story with cars that have clocked up 500,000 kms and more. Nikasil is a good reason not to buy one of those other Teutonic cars.

[toxonix]

I have an '85 M117 5.0 litre in a Euro C126. It has just over 80k miles and sounds and pulls like a beast. It does have rather complicated computer and vacuum controls which I'm having trouble debugging. High idle and hard shifts are common problems, not sure what the cure is.
Haven't had a need to do any major teardowns of M117.

[carl888]

The alloy MB blocks are alusil, not nikasil.  That means you can give them a bore, about 0.5mm from memory.  A properly maintained alusil block should never wear out if you if the correct maintenence procedure is followed.  The car would fall apart before the block.

There are a few versions of the 5.6 liter engine, from the 227 HP USA one to the 297 high compression European version.  The Australian cars were 248, except for the SL which was about 10 HP lower.

Regards,

Carl.

[Ilike300sd]

I found one with lots of blue smoke coming out.  Has about 110k on engine.  1987.  I would guess the smoke is due to bad rings.  Do you know if the smoke would indicate a block issue?  Sounds like the block is pretty bulletproof from the above conversation.

I don't have any info on maintenance or storage on this car unfortunately.  But with the miles it had to be stored I would think.

One thought I had is if I buy it I could possibly try to free up the rings with a solvent soak.  Any ideas are much appreciated.  Thanks!

[jbrasile]

Mike, blue smoke a lot of times indicate bad valve seals and  not necessarily rings. With 110k miles, unless the engine was really neglected, the whole bottom end should be in very good condition.

Tks,

Joe