will a synth swap kill my headgasket???

[JHZR2]

Hi,

My 83 300D just crossed 193K, and I need to do an oil change. While in Canada this summer I happened upon Delvac 1, and so I got 2 gallons, for use this winter.

The past few months, I have noticed a few drops of oil in my coolant recovery bottle. I have also seemed to notice an extremely slow drop of coolant level in said bottle. Both are so minor, I dont know if the level drop is due to temperature changes.

Having searched on the site and come across a few things, I am now slightly worried about doing a change to delvac 1. On another post I made, Larry Bible stated that he reccomends just using 15w40 dino, and thats good enough. But the thing is, the only other use Ill have for these two gallons are in my pickup truck, and that seems like a huge waste to me, so Id really prefer to use it in my MB.

The things Im worried about are as follows:
-if I seep a little oil thrugh the headgasket into the coolant, will this increase with the synth? It should stay thicker when hot, which is good against leaks, but it is thinner the rest of the time, and when it and the coolant is cool, the oil pressure will be high but the coolant pressure will still be around 1atm, so this may help force oil into the coolant. Any thoughts?
-I want to 'clean' my engine as one main purpose of using this oil. But, I dont want to kill my engine. What are the chances of it cleaning up too many deposits and causing poor compression and major blowby? Right now I barely need to crank it at all after glowing it, even on very cold mornings, and it starts no problem... So I think the engine is pretty healthy. I know the oil has been changed every ~3k since new, although I am not sure that it was always with a C rated oil, as the PO (original owner too) seemed to take it to a local oil change place during the later parts of his ownership. I have been using a C rated diesel oil (switch between shell, chevron and mobil) for the past ~20K, and so hopefully those oils themselves have cleaned the engine somewhat.
-I dont want to ruin rubber parts. I have taken care of most all the leaks, but some of the areas around the turbo just look oily. Im not sure that they leak regularly, but the oil and gunk around them makes me wonder. If they leak a bit, thats fine, so long as its minor, but do I run a chance of seals and stuff around the turbo failing?
-If I switch back to dino after using the delvac for 4-5k miles(changing the filter once in between), would any leaks that started most likely be replugged? Does oil consumption that occurs when using synth usually stop after switching back?

I like the idea of a clean engine and easy low wear winter starts... But I dont want to take unnecessary risks or cause things liek oil consumption that dont go back to normal after I switch back to dino.

Thanks for any info you have,

JMH

[gsxr]

Relax about your synthetic fears. Go for it... but be warned that it can take 5-10kmi for the *full* effects to show up, although you may see some changes immediately. For Mobil, the only three to use are Delvac-1, and Mobil-1 15W-50 or 0W-40. DO NOT use any xW-30 weights. Most RedLine and Amsoil products are excellent as well.

I'd be a lot more concerned about your oil/coolant leaks. The correct fix is to remove the head, inspect for cracks, and reinstall. But since that's expensive and difficult, I would attempt to use K&W Block Seal first. This is the only product that has actually worked for me in the past. It's available at most McParts, but is a PITA to use. Read the instruction VERY carefully and do exactly what they say (flush totally before use, mix with hot water, run the mixture, then drain and leave system empty for 24 hours.)

But I wouldn't sweat synthetic causing more problems, it's highly unlikely, and it will help clean out the engine etc. Try a 5000 mile change interval at first, and after a couple changes you could extend that to 7500 or 10k (I do mine at 10k with oil analysis to make sure it's OK.) Up there in Canada (eh!) you should notice a significant improvement in cold starting, due to faster cranking speed.


Regards,

[JHZR2]

ugh, check for cracks?!? Is that the more likely scenario in this situaion then just a bad headgasket?

On the same note, how much should one expect to pay for a headgasket job on one of these motors? The dealer once told me $3k, but when the headgasket went on my mothers plymouth breeze, it only cost somewhere around $800, and I imagine a gasoline engine is harder to take apart then one of these old 5 cyl diesels...

Any info on that is also appreciated. Thanks

JMH

[gsxr]

For your iron cylinder head, it is much more likely to just be the gasket. But if the head comes off, it should be checked, magnafluxed, and have a valve job... then it should be good for another 200kmi. I'd still try the K&W route first.

A head gasket job at the dealer could be $2-3k. At an independant shop, $1-2k. These old diesels are actually more complex than gas engines, and the tolerances need to be closer due to the high compression ratios, high-pressure injection, etc. It's not THAT bad of a job but not easy either. A few people have done it themselves, and posted info on this forum, so you could search the archives. Just don't get confused with the later aluminum heads, which are prone to cracks are cost more to R&R.



Regards,

[P.E.Haiges]

$3000 for a head gasket repacement is outrageous and a rip off.

P E H

[gsxr]

Call your local MB dealer and ask for a quote. Book time is something like 15-20 hours, at $100 per hour, plus parts... which aren't cheap. I'm adding in machine shop work for a valve job, etc in that total number also. Pulling the head off at ~200k, and not doing the valves, etc is very poor economy IMO. It adds up REAL fast. Like I said, it should be significantly cheaper at an independant shop. But I was quoted ~$1500 for the job on my OM603 at an indy, and that was for a straight gasket replacement, no other work. Call up some shops and ask, I'd be happy to hear other quotes, just make sure you get details of precisely what they'll be doing for the money!

BTW - This is exactly why I do these jobs myself, and buy the tools needed! :p :p


Regards,