valve job? - Page 14 - PeachParts Mercedes-Benz Forum

ROLLGUY · #**196** 05-06-2018, 10:57 AM

Quote:

Originally Posted by Father Of Giants

...................
Rather unlikely but ALDA may need to be checked out.

............................

Often the boost signal is not present, or is weak because of a clogged banjo fitting on the manifold, or clogged switchover valve. I like to run the boost line directly from the manifold to the ALDA. You can perform the following test to find out if you are getting a good signal to the ALDA: remove the banjo bolt from the ALDA and start the engine (don't loose the crush washers!). With your finger covering the outboard side of the fitting on the end of the hose, rev up the engine and hold it around 2K RPM. Then hold the fitting against the ALDA where it would be if the bolt was holding it. Do this several times, getting a good seal, and each time the engine RPM should increase without changing the position of the linkage being held steady with your other hand. If the engine revs increase, your boost signal is good. If no change, find out why and fix it. Test again......Rich

funola · #**197** 05-06-2018, 11:12 AM

Quote:

Originally Posted by allenying

................

in the winters before this, it would take a bit to get power as well, but i didn't have the nailing, maybe there was some smoke but not as much as now.
i thought it seemed like low compression would lead to delayed reaction when cold,
................

I didn't know this was an existing problem, before we discovered the tight/ burned valves. I think the occasional nailing you have on cyl #1 now is not due to injector #1, but due the exh #1 valve not sealing well. IMO, the low power for a second when cold from a standstill is due to something else, not related to low compression on #1.

funola · #**198** 05-07-2018, 11:13 AM

Quote:

Originally Posted by Father Of Giants

IP pressure is nothing to worry about...if it was failing your car would be gutless even fullly warm. Or barely even run.

Check throttle linkages, oil em up.
Check fuel filter, air filter,
Rather unlikely but ALDA may need to be checked out.

Personally, when my car was painfully sluggish, a diesel purge and new filters solved that issue

All that was done. We didn't physically check the ALDA but we did do a 0-60 and it was around 14 to 15 seconds IIRC which is within normal range.

allenying · #**199** 05-15-2018, 01:42 PM

out of everyone i've talked to over the last month, forum members, mechanics, machine shops, parts shops, etc, 2 have recently mentioned that sometimes a rebuilt head will not pair well with an older bottom end, claiming new fresh tight heads on an old block is more than the bearings can handle, or that it will cause blowby or oil leak/burn/smoke. and they would rather use a known well running head that has not been fully rebuilt, instead.

but so many have said swapping a rebuilt head, or rebuilding your own head, would be no problem. sounds like it's always a gamble either way, but more likely to be ok...

the rebuilt head i'm buying was actually rebuilt in 2005, the receipt from the reputable machine shop said it was cleaned and checked, valves tested, head resurfaced, for $180 tax, and does not look like it had been used since then as it is "clean as whistle".

allenying · #**200** 05-15-2018, 02:51 PM

fucso's auto salvage sent me pictures of the rebuilt head, i uploaded them to this post but i also put them on my google drive in case you need to zoom in more...

https://drive.google.com/open?id=1ulm-hwWpo9DLesh7tI7n7J5YS0PDtfLT

am i wrong to think the surface rust is a cause for concern? he said it's not, but why pay $550 for a head with some surface rust right?

for $550+ shipping, maybe i should consider the head that came from a well running engine that wasn't compression tested for $400... or just go through the lengthier process of of getting my head rebuilt.

allenying · #**201** 05-15-2018, 04:28 PM

ok upon closer look, those squiggly glow plug lines, in pic 3 and 4, mean this is an earlier model than 85 turbo engine... that right?
thanks.

Mike D · #**202** 05-15-2018, 04:42 PM

Yup. Probably a pre-81 head.

The surface rust means nothing. A quick swipe or two with some steel wool soaked in ATF will clear it right up.

I'd be more concerned with the thickness of the head and pre-chamber protrusion.

OM617 deck height

barry12345 · #**203** 05-15-2018, 05:09 PM

That head posted might also be from a non turbo engine. I suspect the valves seats etc may have been beefed up with the turbo engine heads.

ROLLGUY · #**204** 05-15-2018, 10:52 PM

Agreed- That head is definitely not the right head for your turbo engine. Pass on it and get yours rebuilt, you will be better off.

allenying · #**205** 05-25-2018, 04:47 PM

well it's not all done yet, but this is what's happened since last time.

I thought I was dropping my car off with willy in great neck on sunday, to pull the head so i could bring it to a machine shop. he looked at the idle adjuster bolt on the injection pump and said it’s not the gold one, thinking it was a fuel delivery issue. i looked and it’s dirty from 5 months ago, I am certain we put a gold colored genuine mercedes part from fcp euro.

he wants me to order it from the dealer, bring it back tuesday and will change that and do a valve adjustment himself, and test the turbo.

I told him i already did 3 valve adjustments and I don’t want to pay for it again, he said let me do it to be sure, i won’t charge you a lot, $50-$60.

he says he will be able to feel while doing the valve adj whether or not they are seating properly. which we also already did, pushing to see how firmly it's in place... it was slightly less firm than even the intake valve on cyl 1. but he said he can turn the valve and feel it...

i figured sure, i'll do it his way, at least he's able to take further steps, pull the head, have me bring it to the machine shop, and put it back in, which saves me money and him time.

the other shops would only do it if they were getting the full job, $3000+, so willy is kind of in between those shops and DIY.

next day i tell him the dealer can get the parts faster if he calls, he says ok, that idle adjuster bolt he had layin around should be fine, don’t worry just come and we’ll do valve adjustment.

in the mean time i also picked up a banana/cigar hose and put it in, since i previously had a straight synthetic rubber hose from when i ran bio. figure it's one more thing to get back to normal.

i go back thursday, we’re waiting for my engine to cool and he changes his mind, i tell him again that we did 3 valve adjustments, they didn’t stay at spec, i have low compression in cyl 1.

he says you your valves are burned, i have that engine over there, from an 85 turbo, the bottom was no good, the head is good, come back tmrw morning, help me get it off and you can have it, bring it to the machine shop, bring it back and he will swap. which was my original plan, but now I have a donor head to save time.

seems like he has a lot of cars taking up space and trying to minimize the amount of work, which is why he wanted to avoid pulling ahead if possible at first, but then realized he may as well go straight to the head.

so i've gone 3 times now, and only on the 3rd visit was anything done, pulling the head off the spare engine that was already pulled out. he hasn't charged me anything, the previous customer swapped a full engine and left it. the machine shop i went with was the same one he recommends, magnum automotive.

maurice at magnum also reminded me that the piston rods are known to bend on the 617 engines, so if i have low compression, there's always a chance that happened, but i think/hope it's more likely the exhaust valve after all the tests. so i guess we'll see after pulling my head if the pistons are reaching the same level...

he also mentioned that driving for too long after a valve adjustment is due will burn a valve, making the lock nuts loose, which is exactly we found when doing the 1st valve adjustment.

-

on a side note, i drove my friend's 85 300TD california spec this week, and it has more pickup than my 85 300D non california, even before i had the rough engine issues. i know there are a lot of potential factors, throttle linkages. maybe the rebuilt head will fix it, or maybe it's the turbo. i can get up to highway speed w/o problem, and my 0-60 time was pretty close to normal, it's just the initial pickup, which i thought was normal, but his wagon accelerates from stand still really fast, it's actually kind of sudden like a modern gasser.

vwnate1 · #**206** 05-26-2018, 12:46 AM

Good to see something going on at least .

OM617 engines don't bend rods. the later 6 cylinder ones do .

allenying · #**207** 06-27-2018, 02:38 PM

thanks for the heads up on rods not bending.

small update:
so the donor head took 3 weeks to be rebuilt, $400 plus tax. probably would’ve been faster at the $550 place. but I’m ok with waiting and saving.

in that 3 weeks someone suggested doing a 4th and last valve adjustment, just in case it was some buildup was pushing the first valve to be tight, not letting it close all the way, that could have broken loose since, he said it’s happened before. slim chance but I figured why not, good practice on doing valve adjustment myself.

1st exhaust valve was tight, 0 clearance, as expected. but this time, i couldn’t even get it to spec. after lowering the bottom nut, i would turn the top but to meet it, but then it would get caught or catch, and spin the spring and everything. except i would hold the bottom nut, effectively raising it back u as everything else was spinning clockwise.

i didn’t have the valve holder tool to hold the hexagonal piece to stop it from spinning. i tried using a large screwdriver to block the piece from spinning, it didn’t work.

I got the nuts pretty far away from each other to see if I could see any stripping, can’t see any but maybe it’s hidden.

the furthest down I can get the top nut is for a 0.15mm clearance before the nut grips and turn everything.

so is the top nut a closed end nut? is the valve is bottomed out? is this any more indication of the valve or seat being burnt? anyone experience this before? just curious, i might have this head rebuilt to sell if the head swap goes smoothly.

is there a good diy spring clip / valve holder wrench like the hazet 2769-3?

anyway, going to pick up the head and get it swapped in the next couple wks.

thanks.

vwnate1 · #**208** 06-27-2018, 08:26 PM

Yes, the top nut is closed .

The valve or the seat has prolly recessed .

I had this exact problem on my 1982 240D's first valve, the seat had recessed a little bit then the valve's head "tulipped" , I wound up replacing all the valves, guides and seats etc., etc. when I fully rebuilt the engine .

allenying · #**209** 06-28-2018, 12:00 AM

thanks, it's reassuring to know that even at 0.15mm clearance, instead of the full 0.35mm, the symptoms are more mild, engine isn't shaking or kicking, smoke is less, and there is just some nailing sounds. i don't expect it to last and plan to move forward w/ the head swap finally, but at least this holds me over for a smoother ride, the shaking and smoking was giving the old diesels a bad name!

i may decide to have my head rebuilt to sell if the donor head works out ok

allenying · #**210** 08-08-2018, 05:16 PM

so i finally picked up my rebuilt donor head, and was telling the machinist how i did a 4th valve adjustment, and could only get the 1st exh valve half way to spec, the top nut wouldnt go down enough, but the engine is running smoother for over 1 month / 800 miles now,

he’s suggesting i could pull the top nut off and he could grind it down to get more clearance.
i asked around and it sounds like that would weaken the top nut which wouldnt be good with the lobe hitting it, and a safer move would be to shave down the inside of the top nut, or to shave down a few threads off the top of the valve, to then get the extra space to get the valve to spec.

i’m trying to visualize this... but doing either will shorten the length of the valve, no? and then it might not extend enough when the lobe pushes down on it, right? and also might not reach as far when the lobe is pointed away...

has anyone done this?

if it did work, i know this isn’t the correct way to address this, but if the engine runs smooth for 2-3 months after a valve adjustments halfway to spec...

i’m just putting this off the head swap til summer is over... when i can deal with not having a car for a week.

any thoughts?
thanks,