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24th August 2014, 04:23 PM #1
Dances with splinters
- Join Date
- Jul 2005
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- Oberon, NSW
- Age
- 63
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- 13,359
Any McIvers out there who can help determining whether worn valve stem or rings?
Unsurprisingly, our old '95 Mitsubishi Magna has started blowing smoke.
300K km on the clock and still doing 1000+ km per week. Can't complain, but still...
Now, it has been a loooong time since I've had any interest in (re)building motors and I don't have even a fraction of the mechanics tools I used to anymore.
I suspect that it's a worn valve guide, not rings, that are the culprit... as she has a distinctly louder - than before - valve tap for the first few mins after starting. Sadly, I don't have the proper kit to do a compression test and confirm it one way or the other but I'd like to at least get an accurate idea of the cause before I place her in the hands of someone who does.
From my miserably failing memory there were indicators - such as when it blows smoke - that were fairly reliable pointers. Can anyone improve my recollection? Or have ideas as to how to do a comp test using common household utensils?
(FWIW, she only blows smoke when taking off after a long idle or after working down thru the gears to pull up. If she blows smoke at other times, I don't see it... gotta keep my eyes on t'road, dontchaknow?
)
- Andy Mc
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24th August 2014 04:23 PM # ADSGoogle Adsense Advertisement
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24th August 2014, 07:03 PM #2
GOLD MEMBER
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- Apr 2006
- Location
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Skew, I think it sounds like the valve stem seals are RS .
There may be other things that are worn with 300K on the clock, but I think the source of the smoke at start up is the valve stem seals.Brad.
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24th August 2014, 07:49 PM #3
SENIOR MEMBER
- Join Date
- Dec 2005
- Location
- Canberra
- Posts
- 3,260
Consistent smoking is rings, while valves show more at startup. So if there's a big blue cloud when you start in the morning, it's pointing towards valves, but if it's not till you're moving, its rings.
More than normal valve train clatter is generally indicating that the hydraulic lifters aren't getting hydraulic-y enough which could indicate that you're loosing oil pressure somewhere in the engine...or that the lifters are all gummed up!
My $0.02 would be the valves. But a compression test is a much better way of diagnosing it!
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25th August 2014, 08:56 PM #4
Dances with splinters
- Join Date
- Jul 2005
- Location
- Oberon, NSW
- Age
- 63
- Posts
- 13,359
Thanks fellas, that was the track I was thinking down too.
It's just that it's nice to have some idea of what my mechanic will say once he gets his hands on it. Gives me an idea of how many pennies I need to dig out from under the vege patch.
- Andy Mc
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25th August 2014, 11:55 PM #5
GOLD MEMBER
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- Jun 2005
- Location
- Helensburgh
- Posts
- 7,696
Do not increase the compression if the head comes off. If the mechanic wants to pull the head off and overhaul it an increase in compression will push oil past the rings on a motor of that age. I used to refuse to do it as the customer was never happy with the result and we always found extra stuff that needed doing blowing out the quote.
CHRIS
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