First Real Problem in 320k Miles - Page 2 - PeachParts Mercedes-Benz Forum

TnBob · #16 05-27-2015, 02:19 PM

1950psi is supposed to be pop pressure.

If you kept the old nozzles you might even try one of those.

cooljjay · #17 05-27-2015, 03:46 PM

Were these properly rebuilt, lapped and balanced injector rebuilds? Or they done on the kitchen table?

Carpenterman · #18 05-27-2015, 11:26 PM

Don't know what "properly" means, although I used a homemade pop tester, a shim kit, and a glass lapping surface. Not a kitchen table, but one in my barn in view of the horse and milk goat.

Does that matter?

Whatever, the injectors ran fine for 40k miles before this problem occurred.

cooljjay · #19 05-27-2015, 11:52 PM

It matters if they were done with the correct tools or just unscrewed and nozzles replaced like a lot of folks do...

I would have to re read the service manual but I thought it was said that nozzles needed to be checked/rebuilt/replaced every 50k.

I have a set of rebuilt injectors with monark nozzles that I moved to the 78 that probably only 10k on them and one nozzle has an issue...monarks aren't some magic brand they still have issues...and with our crappy fuel its even worse if you don't use additives and cleaners..

biopete · #20 05-28-2015, 06:10 AM

Quote:

Originally Posted by cooljjay

It matters if they were done with the correct tools or just unscrewed and nozzles replaced like a lot of folks do...

I would have to re read the service manual but I thought it was said that nozzles needed to be checked/rebuilt/replaced every 50k.

I have a set of rebuilt injectors with monark nozzles that I moved to the 78 that probably only 10k on them and one nozzle has an issue...monarks aren't some magic brand they still have issues...and with our crappy fuel its even worse if you don't use additives and cleaners..

I don't think poptesting / balancing injectors is a 50,000 maintenance item in the factory fsm. But it should be in the greaser's service manual. it is very good to check that often if running single tank wvo especially.

In my experience just removing and replacing the nozzles with the original shim works fine. And certainly if you have a bad nozzle , a new nozzle will be an improvement even if it isn't "properly balanced". I had a pop tester and used to pop test them and they were always right around the mark within the spec. But that could have been luck.

cooljjay · #21 05-28-2015, 04:31 PM

^^ Agreed! I have to find that blurb, My 78 has the manual but my friend took her to work so I can't see if I read it in that package. I know I was shocked when I got my 78 and was reading the service records from the dealer, they were replacing the injectors like spark plugs...10,000 miles, 40,000miles With the factory replaced injectors, my 78 must have seen a dozen sets in 200k miles.

I still recommend member Greazzer for injector service, good pricing and good reviews!

Carpenterman · #22 05-31-2015, 04:49 PM

O.K., an update. After two MMO soaks and six days delay waiting for heat shields, I assembled a fitting using an old injector to do a leak-down test.

The air is definitely leaking past the piston. It's leaking so badly in the cylinder that my air compressor could hardly keep up. It's a medium to small size (I don't know what the cfm is or if it really matters). Remember I had 80psi compression dry and 160 wet.

I think the top end is good. I measured the valve protrusions on #3 and they are the same as the others. But you could really hear the air escaping from the oil drain channel in the back of the head.

So I guess I'll just reassemble everything and see if maybe running it improves things in the hope that if it is stuck rings, they will free-up. I pop tested and rebalanced the injectors while they were out to just to make myself and Cooljay happy.

So stuck rings, broken rings, or maybe a hole in the piston. Has this ever happened in a 617?

I have a parts car engine that I could swap in using the wagon head, but it's been sitting for 4 years and has 240k on it.

What are all y'all's opinions?

cooljjay · #23 05-31-2015, 07:46 PM

I've had stuck rings on both my rigs...well and my 71 dart....

It was always fun on some random hotrodding freeway trip when the ring unstuck and I gained a burst of power

We have a curve here on the main drag...I LOVE to drift from the slow lane at 65 into safeway parking lot

Any who....point being....don't worry about it to much, keep the car maintained Removethe EGR system, run Lucas, seafoam and make sure to do oil changes and valve adjustments before they are do...the more oil changes one does...the more carbon you remove from the engine and the better job the oil does cleaning up....then drive the damn thing like a Porsche...

The 78 was ran on wvo, burns oil like hell...and I have been driving it non stop since 2012 with three trips to Cali on it...

You may get a lot more years out of driving it before you have no choice but to pull the engine..

Stretch · #24 06-01-2015, 01:01 AM

Quote:

Originally Posted by Carpenterman

O.K., an update. After two MMO soaks and six days delay waiting for heat shields, I assembled a fitting using an old injector to do a leak-down test.

The air is definitely leaking past the piston. It's leaking so badly in the cylinder that my air compressor could hardly keep up. It's a medium to small size (I don't know what the cfm is or if it really matters). Remember I had 80psi compression dry and 160 wet.

I think the top end is good. I measured the valve protrusions on #3 and they are the same as the others. But you could really hear the air escaping from the oil drain channel in the back of the head.

So I guess I'll just reassemble everything and see if maybe running it improves things in the hope that if it is stuck rings, they will free-up. I pop tested and rebalanced the injectors while they were out to just to make myself and Cooljay happy.

So stuck rings, broken rings, or maybe a hole in the piston. Has this ever happened in a 617?

I have a parts car engine that I could swap in using the wagon head, but it's been sitting for 4 years and has 240k on it.

What are all y'all's opinions?

Remove head (sorry)

Carpenterman · #25 06-01-2015, 12:13 PM

I know it, but I'm in denial.

BillGrissom · #26 06-01-2015, 01:30 PM

Sounds like my 1985 300D engine. It failed at 330K miles. I heard a sound like a ball bearing was bouncing around, pulled over, then it went away. It had done the same ~1 yr prior. This time I drove 3 miles and engine seemed to drag, died at idle, turned over real slow, but wouldn't start. Towed home, disassembled, found 3 pistons w/ missing chunks around the ring grooves, w/ #1 all beat up like something was bouncing around in the cylinder. For 2 years prior it had been getting hard to start in the winter (needed block heater). I used the HF kit and measured ~250 psi in most cylinders a little before this. My method was OK since I measured ~405 psi in all cyl of the replacement engine (~3 yrs ago). Some claim these are "1M mile engines", but might have been the 1970's non-turbo versions. You are right about where I am. I never pushed the engine and the prior original owner was a middle-age lady who babied the car.

If you want to proceed carefully, buy an "endoscope camera". I got one for $18 on ebay. USB w/ LED lights. But, you would have to remove a pre-chamber to view the pistons. You might also view the #1 cyl walls w/ lower oil pan off. Mine had some wear streaks on the walls of several cylinders, and stories suggest #1 fails first, perhaps from more temperature variations. I can't imagine that injector pop pressures would explain much. I found my 1984 engine had 3 non-turbo injectors (popped at 1600 psi), but changing them didn't noticeably change the idle.

Carpenterman · #27 06-03-2015, 01:01 AM

After arrival of the heat shields, I buttoned the motor up, bled the injector lines and took the car out.

Alot of blue smoke at first as the MMO got burnt off. Still missing cylinder #3. Even after warming up and an italian tuneup, the cylinder is missing and there are puffs of blue smoke. Strangely enough, the car runs pretty good on acceleration and at higher rpms even with the missing cylinder. Idle is pretty bad, though. No unusual noises from the engine.

I soaked the parts engine with MMO and turned it over a few times in anticipation of a block swap. I'll continue driving the wagon under the slim chance that if it is a stuck ring it may free up (I left about a quart of MMO in the crankcase). Also with the chance that the motor may self-destruct.

I'll check the costs and decide soon whether to do the swap. Since it's a wagon and the parts car is a sedan, I'll have to reuse the head. If I do the swap I might as well do all the gaskets and seals. I wonder if it's worth rebuilding a 320k head to put on a 250k block. Does anyone know the approximate costs of a head rebuild? (assuming guides, springs, regrinding and resurfacing)

Stretch · #28 06-03-2015, 10:09 AM

My costs over here are probably a little bit out but I would expect between 500 and 1000 USD for most OM617 head refurbishments. It depends what gets done.

Skimming a head isn't much money if you strip everything down for the machine shop.

The real money ends up in grinding and polishing valves - fitting new valve guides which although are not too expensive from a spare part cost point of view need to be reamed and then the valve seat re-cut - which then probably means the head needs to be skimmed. If you need to replace valves the cost goes up. If you have camshaft trouble - the cost really goes up as you should replace the followers...

...sometimes you see reconditioned heads on offer in the classifieds. In some situations these options work out cheaper than repairing what you've got.

cooljjay · #29 06-03-2015, 03:21 PM

Metric wants 960$ for a non turbo head minus all the doo dads for the camshaft...gives a price perspective...could always contact them..

Mercedes Rebuilt Engines

Maxbumpo · #30 06-03-2015, 04:22 PM

LKQ wants ~$65 for a head you pull yourself, just need to find a turbo wagon in the boneyard....

However I believe the OP's diagnosis is a failure of the rings, not the head, so he can probably re-use his head. I'll bet a competent machine shop can install new guides and clean up the valve seats for $300 or less, if you bring your own parts.