lost compression. no bad HG symtoms. Help please

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ATL240
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lost compression. no bad HG symtoms. Help please

Post by ATL240 »

I have a 1990 240sx as my daily driver, 100% stock ka24e, I was getting the emissions test done and all of a sudden it turned off while on the rollers :icon-redface: So we pushed it off the machine and it's just sitting at the parking lot now. I went back and started doing a compression test and cylinder 1 reads 0. I will test the rest when I tow it home. the car has never over-heated and made no noise or blew white smoke when this happened. What do you guys think it could be, and how could I check it? I'm not good at doing a leak down test.
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Re: lost compression. no bad HG symtoms. Help please

Post by shift_down »

0 means a stuck valve I would think.
Check every cylinder and report the numbers.

If you add oil into the cylinder and do the compression teat again, it will either still read 0, or increase a little. If it is still 0, then valve is bad, if it increases, then the piston rigs are bad.
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ATL240
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Re: lost compression. no bad HG symtoms. Help please

Post by ATL240 »

It has a fresh bottom end rebuild,and head . Its has a $30 dollar ebay timing chain kit,I'm hoping it just jumped timing. Do you know if there is any way to check if any damage was done to the valves if that were the case?
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Re: lost compression. no bad HG symtoms. Help please

Post by sil-coupe »

I'd remove the head to inspect for damage. Could be valves, rings, ring lands. I doubt the chain would jump even if it were eBay. What does your fresh bottom end consist of? Stock or aftermarket pistons? I've had head gasket issues without the symptoms of "normal" failures and my worst fear was ring lands.
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Re: lost compression. no bad HG symtoms. Help please

Post by shift_down »

Compression test all cylinders and report what you find. Most likely you will need to pull the head regardless of numbers.
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ATL240
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Re: lost compression. no bad HG symtoms. Help please

Post by ATL240 »

So I peeked in through the valve cover while someone cranked it and the cam does not turn. I can see the chain is still attached on the cam sprocket. I'm gonna be taking off the timing cover to what exactly happened. Hopefully its just a broken chain and the valves are still good.
ATL240
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Re: lost compression. no bad HG symtoms. Help please

Post by ATL240 »

So I took off the timing cover and this is what I found(pics below). I'm going to install a new chain kit and do compression test before re-assembling. Hopefully the valves are ok, I ordered a timing chain kit from my local Nissan dealership. $260 for everything, wish I had gotten it to begin with!



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sil-coupe
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Re: lost compression. no bad HG symtoms. Help please

Post by sil-coupe »

Yikes! That's terrible!
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Re: lost compression. no bad HG symtoms. Help please

Post by shift_down »

Did the chain break?
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Re: lost compression. no bad HG symtoms. Help please

Post by sil-coupe »

Yeah shift it broke! ...look to the right of the crank sprocket, sheared at the pin joint. I've never seen that before. Sheesh!
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Re: lost compression. no bad HG symtoms. Help please

Post by KA24ETZTM »

This is why I you should only go OEM on things like this. Ive heard of the aftermarket tensioners failing too.
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ATL240
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Re: lost compression. no bad HG symtoms. Help please

Post by ATL240 »

Put the timing chain on yesterday and did a compression test. Perfect Numbers!! I put all back together today and it's running stronger than ever, and it's so much quieter with the Nissan tensioner compared to the cheap china junk it had. Paying $250 at Nissan for the chain is definitely worth it. I can now drive with peace of mind.

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Re: lost compression. no bad HG symtoms. Help please

Post by shift_down »

Nice! Quick install by the way, it would've taken me a week or so.
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Re: lost compression. no bad HG symtoms. Help please

Post by sil-coupe »

Good job man! Thanks for posting the update. Glad its running better! Thumbs up for going Nissan! God I love the way Nissans stuff is packaged... Mostly o think I just really like the label lol.
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