Interference engine to Non-interference engine-Just a thought. - PeachParts Mercedes-Benz Forum

hsahai · #1 06-25-2009, 12:58 PM

Interference engine to Non-interference engine-Just a thought.
This is just a theoretical preposition based on my experience with Isuzu Rodeo 3.2 K V6-SOHC. This engine is Non-interference engine. Few months back timing belt(not chain) broke. Nothing bad happen to piston or Valve.
My observation- Ignition champer is larger than the travel of pistons or valve?

My theoretical prepostion is -----

1- Meassure the elevation of the lobe of the cam shaft- travel distance of Valve into the Ignition chamber.
2- Increase the ignition chamber hight to same lenght as travel distance of valve- by putting head gasket spacer or may be putting 2,3,4 head gaskets.
3- Theoretically- If ignition chamber hight is increased by valve travel distance. Piston will not collide with valve.
4-Possible broblems- loss of some compression ratio, loss of some power
5-Abvantage- NO BENT VALVES, NO DAMAGE PISTON IF TIMING CHAIN BREAKS.

What are your thoughts on this hypothesis.--------?

If anybody has done this? It will be great inovation if any of you want to do this vanture?

waybomb · #2 06-25-2009, 01:14 PM

You'll loose a ton of compression.

You could have custom pistons built ($$$) with thick crowns and relieve the tops for the valves, assuming there's room for the connecting rod when it's all done. But then you swinging heavy pistons around.

Wouldn't it be cheaper to simply change the chain when the job is prescribed?

pawoSD · #3 06-25-2009, 03:00 PM

Yeah, huge compression loss, and it probably would not work....timing chains rarely fail, and when they do, its because it was neglected. Just replace the chain!

GaryF · #4 06-25-2009, 03:18 PM

I bet one of the head gasket layers or spacer fails before the chain too, an alternative would be to use a crank position sensor and cam position sensors to continuosly monitor chain stretch or maybe monitor the position of the chain tensioner to determine stretch.
I'm a lot happier with a dual chain setup than the modern belts that snap without warning.

pawoSD · #5 06-25-2009, 11:53 PM

Same here, timing belts are the worst thing ever, I'll never buy a vehicle with a timing belt engine, which is why I have no VW tdi.

cliffmac · #6 06-26-2009, 12:10 AM

you answered your own question...it's about compression and that's it. Lower compression engines can be non-interference engines but they won't develop the horsepower that interference engines are able to in a smaller (and hence more effecient) arena. So if you want the same performance from a non inter engine you would have to make the engine larger thus negating any performance gained. Both in weight/fuel economy and the associated handling loss of such added bulk. I haven't heard of any decent non-interference engine on a performance engine since the hemis of the late 60's or early 70's muscle cars (and you know where they are now)..And don't even get me going on diesels.....it's simply an enginering fact....hell, do they still even make a non interference engine that can be sold in the US...I would think that the EPA would have strangled by now......

pawoSD · #7 06-26-2009, 12:45 AM

Yeah there are extremely few non-interference engines to begin with, probably no recent ones either.

I can remember I was looking on craigslist at a 300E 4matic with 240k on it or something that had a failed timing chain, the woman wrote in the ad "timing chain just needs to be replaced then the car will be good as new" I e-mailed her and informed her that the damage was likely extensive and that the engine may well be toast. She rudely responded that the engine was of the non interference type and that her price (3800) was fair and that I should learn something about engines before I say what type it is. I told her that MB never even produced a non-interference engine, including the M103, and that she was dreaming on the price. It only went downhill from there....she was pretty darn sure that it was the non-interference type....ah well, some people are too dumb to be helped I guess.

OldPokey · #8 06-26-2009, 10:51 AM

Let's hear it for sleeve valve engines!

lkchris · #9 06-26-2009, 11:01 AM

Quote:

Originally Posted by pawoSD

Same here, timing belts are the worst thing ever, I'll never buy a vehicle with a timing belt engine, which is why I have no VW tdi.

Yes, I got one recently somewhat against my better judgement (this issue). A more sensible around-town vehicle than the GL. The belt rubs and squeaks on cold startup--30K miles before scheduled change.

Guys on the TDI forum actually try to come up with reasons belts are better, but they aren't convincing. USA needs A- and B-class.

cliffmac · #10 06-26-2009, 10:08 PM

yes, the old sleeve block. I had a Peugeot 504D with the sleeve block....interesting engines for sure....

pawoSD · #11 06-27-2009, 12:25 AM

Quote:

Originally Posted by lkchris

Yes, I got one recently somewhat against my better judgement (this issue). A more sensible around-town vehicle than the GL. The belt rubs and squeaks on cold startup--30K miles before scheduled change.

Guys on the TDI forum actually try to come up with reasons belts are better, but they aren't convincing. USA needs A- and B-class.

That's scary! 30k before required change....so it only has like 40k on it?

The other scary part is the ridiculous amount of work and $$ involved in replacing that annoying belt every 70k....that is, if it doesn't break before it is replaced.

So far I have put nearly 80k on my two MB's (almost 74k on the diesel and just over 6k on the gasser)....with 0 issues. I did have the chain replaced on my diesel around 212k....as it was quite stretched.....that was nearly 70,000 miles ago, and it has only 1/2 a degree of stretch now. Its going to last a looooong time.

The timing belt was one of the main reasons I moved so quickly to get rid of the Rav4 in my sig....it was like 9k overdue for a timing belt....and I didn't want to pay $800 for that, so I sold it quick and got the 300E.

M103 timing chains last for a loooong time with proper oil changes.