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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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Discussion Starter #1
I'm utterly confused.

I looked at these instructions (since it seems specific to the 980 version of the M104):


(must scroll down away's).

1) there's no mention of removing the guide pin(s)???

2) there's no mention of removing the tensioner (chain tensioner).

Are the above not necessary on the 980? Only on the newer M104s?
 

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W124
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5,003 Posts
Robert,
I read them and while I think they aren't very well written, they mention pulling the pins and the chain tensioner. What I don't get is the lack of mention of any sensors, wiring, etc. Also, they talk about the potential for abrasives dropping into the cylinder wall/piston gap and then they talk about using WD-40 to clean the top of the piston. Hello? Why would you wash (with WD-40) any carbon and abrasives down onto the rings? It seems to be a recipe for disaster. If I clean piston domes when the head is off, I do it dry.
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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2,957 Posts
Robert,
My experience is with the later hfm 104's, in that case,
The chain needs to be relieved of tension as there is an upper guide that pushes the middle of the chain ( between cam sprockets) which is fixed to the cover. If chain it's actually pulling on the cover. I've gotten covers off without loosening but also slightly bent, and chipped the guide.
If you want to use the tool, pm me. Just pay shipping there and back.
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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The "if" means the tensioner will tighten if you remove the uppermost guide. The tensioner is a ratchet like apparatus. If the guide is not pushing against it by keeping chain tight, it will allow the tensioner to expand. (Ratchet out, can't push back in)There is a correct order installing tensioner so that it preloads correctly.
It sounds more difficult than it is. I used a SWAG tensioner, and all is well. INA is also not terribly expensive.
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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Covers are different due to distributor. Principles are the same.
The screw they talk about is more like a "cap" in that it prevents the pin from working back out. It screws in over the pin to keep it in place.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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784 Posts
Discussion Starter #11
Okay, so...

remove the tensioner regardless.

Then stick that swag tensioner tool in there to keep things nice and tight until you remove and replace the timing cover?
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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Yeah, tensioner is one of those "while you are in there things". Can't recall what the fsm says for tensioner durning the work, but yeah you want it tight enough it doesn't come off the crank sprocket.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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784 Posts
Discussion Starter #13
Starting at 2:30:


He doesn't remove the tensioner.

He uses a screwdriver to pry up the chain to get that upper guide out. He also then talks about using a crescent wrench on the cap to get the chain loose enough to get the guide out.

Anyone else uses those methods rather than pulling out the tensioner???
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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That guy also doesn't know what he's doing. He had to redo job a few times and gasket still leaks. Find the fsm in the stickies, it will tell you how. I think I just loosened tensioner when I did it.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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784 Posts
Discussion Starter #15
Okay, removed the tensioner. No big deal. Then just pulled out the timing cover.

One thing on this m104.980, there are not guide pins to pull out, so I guess I'll return that tool.

BTW, does one have to put goop/gasket sealer underneath the green U-gasket? I'm having to scrape all that old stuff that's there. Wondering if I need to do that as well. Or if they just did that to hold it in place?
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,204 Posts
Do not put any gasket sealer on the green seal, except for a small dab of Hylomar (and nothng else) at each end of the U groove.

Traces of old sealant is a dead giveaway of amateur mechanics handywork.
 

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1994 e320 coupe (sold), 1990 300CE ($400 beater)
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784 Posts
Discussion Starter #19
what's the secret on getting that plunger out of the housing?

hate to bang on it to get it out.
2619149
20200202_132229-1.jpg
 

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1989 300E
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Any body can help me with my 300E 1989. Low oil pressure. In cold engine the pressure is high but when is hot the pressure goes to 0 in idle. I am afraid to brake the engine.
 
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