Engine rebuild?
I own a 1993 300GD 463 with STT turbo and 90k miles on the clock. I have only owned it a couple of months and although it runs ok (with a few minor issues), I wanted to get it checked out with a view to gradually putting it into top nick. My local Merc garage had a look at it and are giving me a list of things to sort.
The major issue, which they couldn't confirm without more time (and money), is the timing chains which are apparently out of sync and may well have done major damage to the engine. It seems to run ok but is slow and has the odd power 'dip' which I thought was a filter issue. But if the chains have caused major damage, does anyone have an idea what an engine rebuild would cost (not by Mercedes!)? Is it cheaper to put in a replacement engine?
Hi
Assuming your 300 still has the original engine (OM603) albiet turbocharged then there should be only one timing chain fitted. These engines in 4 and 5 cylinder form were known for stretching chains but i have not heard of a 6 cylinder to do it and the others were a bad batch of chains used by MB and when the engines were 12 -18 months old. You need a more technical person than me but if it is still driving and not making any engine noise then even if the chain has stretched then it should be able to be replaced with out a full rebuild which the engine at that milage should not need. If it is just worn with age (unlikely again at the milage) then the job is a little more involved but still not bad. I have heard that the chain should be changed every 100,000 miles but i dont know any body that has ever done that and i dont think MB recomend an age or mileage. Only change if worn or stretched?
Chains are £141 + vat from MB and as i remember 2-3 hours to swop just the chain if you are a pro + a few comsumables.
Hope this helps
Chain stretch is a possibility but so is timing gear wear. One would expect more than 90,000miles but the previous owner(s) might not have been too diligent about changing the oil.I don't know this engine but I assume it has a chain tensioner - this might also need replacing.
Take care not to get into a spiral of replacing random parts based on suspect diagnosis.
Personaly, if I were keeping the car I would rather repair than replace as you won't know the provenance of the doner. Rebuilt engines often have the part that broke replaced and sold as working but one has no way of knowing what is next in line to fail.
All that said if you can find a good engine in a 124 saloon then a swap could be done in a day easily.
On what evidence do they base their diagnoses as 'chain out of sink'??!! It runs with no horrible noises right? Doesn't smoke a lot? Starts fine? If there are any performance issues, it's more probable that it's something to do with the fitting of the after market turbo. Maybe the injection timing was adjusted incorrectly? I'd leave the actual engine alone.
My understanding and experience of timing being out, is the engine does not fire, if it starts, it would be backfiring, suffer serious loss of power, overheating and excessively smokey etc, etc...
CORRECTION: My apologises, I notice, I have jumped the gun again, I have re-read your thread and just caught-on that you have a W463, I had it my mind you had a W460. The 463 does has makings on the cam shaft cog and a corresponding mark on the bearing cap or some where there. (This paragraph and the next one, has been re-edited with deletions).
The injector pump timing is critical, if this is out, you would have almost similar faults as listed above. The timing adjustment for this should be done by a competent Diesel garage.
The injectors, if not spraying correctly may cause issues, you can expect difficult starting, smokey engine, poor fuel consumption and performance. One can, as I have often mentioned; at least twice a year, add injector cleaner additives to the fuel tank, on full tank for the cleaning process to occur over the use of the engine. Alternatively, an equipped garage can use intensive cleaning agents to run through the engine to clean the system. Should this not work, the injectors may need servicing. Please note, injector cleaners for Diesels' and Petrols' are different, read the label on the bottle, for a correct choice.
Any excessive wear in the timing chain or poorly performing chain tensioner will be indicative of a noisy and rattey chain, heard, on the runing engine.
Cheers,
I’d be amazed if that diagnosis was correct, simply doesn’t add up. Merc. Main dealers should be avoided at all cost, the vast majority will be completely out of their depth with anything that can’t be diagnosed by plugging it in to a diagnostic computer. If they can’t figure it out they’ll just throw your money at replacing random bits.
You mention the odd “power dip”. Could be filters. Any competent garage can change those. More likely, but pretty impossible to diagnose over the internet, some sort of boost control issue with the turbo.
I’m in the Shropshire area but don’t know of any G Wagen specialists in this area. You don’t need one though, there’s nothing specialist about them. They're mostly MB parts bin from E Class/Vans etc. Find a competent trustworthy garage, maybe a 4x4 specialist and you’ll be fine.
Russ
Agree with Russ, find a good garage.
While your at it, have the whole air intake system looked at, if it's anything like what TB turbo's did, it's likely to be a mess. Metres of pipe restricted even more by going into a too small aftermarket air filter, resulting in lack of power and high temp when being pushed.
Shaun had his replaced with parts from a G350 TD, the air now goes through the original air filter, and travels about a quarter of the distance then the way TB's did it, and through much larger pipes.
Rebuilt th engine On account of slack timing chain ??? A bit drastic I think. There is a chain tensioner that takes care of the slackness. This is adjustable .Try to get hold of a Haynes Owners workshop manual for 123 series ( ISBN 1 85010 114 0) this will cover your engine. Plenty of good info there and good drawings as well as troubleshooting sections.
In my personal experience, the STT conversion was not really worth the trouble. One thing I recall is the use of fully synthetic oil once the engine is converted. I wonder if the previous owner really stuck to this discipline.
Pistonhead sums up the checks very well. A good mechanic (who also follows the instructions and does not improvise) should be able to carry out these checks at a nominal cost. I also agree with the advice to keep away from dealerships. They simply do not either have the "old mechanics" in the shop or do not want to spend too much time on old cars when they can maximize their profits in the "plug in" diagnostic ways.
Hi, if you are concerned about the timing chain you should start by checking the injection pump timing, any experienced mechanic should be able to do this with the good old fashioned spill timing method, from memory 24 degrees BTDC is the figure you are looking for. These engines did have a bad batch of chains around 1992 that were known to stretch, we had one on a K reg 300D. A genuine quality chain, manufactured by IWIS, should be available from someone like KMS for less than a dealer would charge you, and they are simple to fit, and self tensioning(not adjustable). These engines were from W124 series cars, not W123's so be careful what service manuals you get hold of, and valve clearances on these engines are taken care of by hydraulic tappets. Make sure the fuel filters are all clean, main, primary and usually one in the tank. The other thing to cause intermittent power loss is air ingress, check all your hoses and connections.Make sure the throttle linkage is opening the injection pump up all the way to the stops as well. The only other thing to say is that these things don't fly, even with a turbo, so don't get too carried away with your expectations of it! I doubt very much you will be needing an engine re-build. Hope this is of some help, keep us posted on your progress.
Well what more can I say, it's all been covered above. I replaced teh timing chain on my 92 300gd at 180k miles and the mechanic checked the timing before he removed the old one and said that there was no decernable stretch. So as everyone else has said don't spend money on random items because someone tells you to. The timing is easy to check, remember to rotate the engine in its normal direction only. You would be doing a good thing to sort out the air intake setup that TB installed as Mark suggested that's probably where your loss of power is coming from, but yuo will require parts off the 350gd which you will probably only get used from Germany.
Put up a pic of the G and engine
I have been looking at afriends 300TD today, same engine as yours but no turbo. I found that the rocker and inlet manifold breather hoses had hardened and cracked - this is giving problems of engine idle instability and on driving I thought I could feel a couple of flat spots. Worth having a look as it might be a cheap fix with a bit of luck
Thanks for the great feedback from everyone. I'll keep the forum posted on my progress, and some pics!
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Thanks very much for the quick responses. It sounds like good advice to check the chain and tensioner first before assuming that any wear or mal-adjustment has damaged the engine. So i'll start there. Also the advice on the turbo is probably right. The previous owner didn't do many miles or mistreat the car, but neither has it been serviced properly by the looks. I wouldn't think the turbo has been looked at since it was fitted in the early 90's!
Being completely unmechanically minded, does anyone know a good garage where they really know their G Wagens? I'm in Shropshire / W.Midlands.