N/A FJ20 Build

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defdes
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Re: N/A FJ20 Build

Postby defdes » 18 May 2013 17:07

PM'ed

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Re: N/A FJ20 Build

Postby defdes » 27 Dec 2013 12:41

So after sitting since last November...that's November 2012, I am finally getting around to replacing my head gasket that blew.
It was weeping just a bit out of the front cover and a drip by the #1, I was getting the sporadic temp spikes on my last drive which caught my attention.
This is what I found upon removal and never having dealt with this before, I need a little insight. There are traces that something got into all four combustion chambers, I don't know if it was dirt road particulate that got by my very old ITG filter, but each bore has varying degrees of pitting on the head. All of the combustion chambers were very sooty, not wet, but dry cake. I knew I was running a bit rich, but it is probably also indicative of the blown gasket? There was a bit of melted aluminum in each exhaust port.
I only turned the motor by hand since it was parked a year ago, just twice around to get it to TDC. You can see where the motor was left on the #2 when parked. That discoloration is a lot worse in the pics, I only wiped it down with a gas coated rag and none of those marks can you feel with your finger nail. The piston tops were also quite sooty, but not wet.
You can still see cross hatching on the bores and the requisite scuffing from aluminum pistons (WISECO 10.5:1)
The HG showed nothing dramatic, to my eye at least.
I was hoping to just replace the gasket, do an oil/filter and water change, drive the motor up to temp a few times, then change the fluids again.
Still need to drain the pan, but looking at the stick, there was no sign of water though I would imagine there has to be some in there.
Any input? I know the ?BEST would be to pull the block and re-do it all, and I will probably end up doing that eventually, I just wanted to avoid doing it now if I can.
Pictures show after a rough cleaning.
fjhead1.jpg
1&2
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3&4
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fjhead3.jpg
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Last edited by defdes on 27 Dec 2013 12:44, edited 1 time in total.

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defdes
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Re: N/A FJ20 Build

Postby defdes » 27 Dec 2013 12:42

Block....1 &4 I started to de-scale, 2&3 are wet with gas wash.
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Re: N/A FJ20 Build

Postby bertvorgon » 27 Dec 2013 12:47

I dunno, that looks kinda normal to me.

When an engine sits for a long time, the humidity in the air gets absorbed by the slight carbon layer, thus lifting it and making it appear more "fluffy' that it really is.

If you know you were slightly rich, then that would explain the fuel/carbon deposits.

My thoughts at any rate.

For what it is worth, that is why we tape up the exhaust and intake, so that no moisture can get in, as we get such ranges of temp/humidity change here. It does keep that micro corrosion down to a dull roar.
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1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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defdes
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Re: N/A FJ20 Build

Postby defdes » 27 Dec 2013 12:55

What I find vexing and probably worth the effort of the bottom end check, are those damn pin holes and gouges on the head/piston. I am wanting to not think it was a ring letting go, the 2 visible bores at least, show no sign of that.

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Re: N/A FJ20 Build

Postby bertvorgon » 27 Dec 2013 13:04

Yah, if they were NOT there when you put it together, it does look like some small bits rattled around in there.

Anything fall apart in the intake/aircleaner? I once had a throttle screw go through my motor, closed my plug up, but, other than some marks on things, did no damage.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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defdes
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Re: N/A FJ20 Build

Postby defdes » 27 Dec 2013 14:03

From what I can surmise, there are 1-2 larger "gouges" in each cylinder followed by smaller and smaller ones. I drive a lot on dirt roads here. What I think happened was some rock particles got sucked in past my 10 year old filter and got broken down and spit out. If it were rings or something else, I think the signs would be different and not consistent across all 4 barrels.

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Re: N/A FJ20 Build

Postby bertvorgon » 27 Dec 2013 14:16

I would agree there. With the top of the piston where the ring land(s) are, it looks fine.

It just looks like some thing bounced around, got ground up and spit out.

Even when a ring breaks for the most part, it just stays encapsulated in the grove, at least that has been my experience. It's only when the piston top starts to degrade or collapse, do the ring bits come out...at THAT is usually very noticeable......

This happened on my Toyota.....yet no bits came to the top of the piston. We think it was detonation the broke a top ring, and that let the flame travel down and out an oil groove, ultimately melting the thing.
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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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defdes
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Re: N/A FJ20 Build

Postby defdes » 27 Dec 2013 15:41

That's quite impressing...or depressing.
The only thing I'd be concerned with now is that some of my valve seats might have gotten dinged.

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Re: N/A FJ20 Build

Postby 510wizard » 28 Dec 2013 06:32

How do the plugs look? Gaps closed or smaller, insulator ok, no missing pieces? On the valve seats, fill the camber with fluid (alcohol or kerosene) blow air into the ports, any bubbles on the camber side? Might be a good time to get some better air cleaners if the dings are from external crap.

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Re: N/A FJ20 Build

Postby Three B's Racing » 28 Dec 2013 06:50

Is it possible pre ignition causing that type of pitting?
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bertvorgon
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Re: N/A FJ20 Build

Postby bertvorgon » 28 Dec 2013 08:40

I wondered that also, but, in any examples I looked at, NON had that sharp edged look to them, specially those two triangular shaped ones.

When I had the screw go through my one cylinder, the piston top looked like the edge of John's, small little hits.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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James
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Re: N/A FJ20 Build

Postby James » 28 Dec 2013 11:41

Broken ground electrode from spark plug?
Finished is better than perfect......

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Re: N/A FJ20 Build

Postby bertvorgon » 28 Dec 2013 13:25

I have been re-thinking this......take a look at this link....I see many examples of pitting that looks like yours, specially one from the Volvo Forum.

https://www.google.ca/search?q=how+does ... 09&bih=891

Most of my experience has been from seeing catastrophic failure, so something that is starting maybe is what you have.
As James asked...what was that plug like that came out of that hole? Sometimes the insulator can be a telltale if that cylinder was hot.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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Re: N/A FJ20 Build

Postby Byron510 » 28 Dec 2013 18:31

John, I also wondered about detonation because all chambers look very similar.
Another question is did you ever run real race gas in that engine and did it ever sit for a long period after having run race gas? This could be another source of the corrosion.
If all cylinders took that many hits from FOD (foreign object damage), the the plug electrodes also would have seen damage I'm sure.
I am leaving to detonation or corrosion damage myself.

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