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500 miles since HG replacement

Posted By: outdoorfan

500 miles since HG replacement - 12/09/10 11:43 AM

On my '94 pickup 22re. Recently I heard what sounds like valves ticking (but only under load) that hasn't gone away. Maybe it's pinging, but I don't know. It's something new that I've never had to deal with before. I checked the timing to make sure it hadn't moved. It's right at 5-6 advanced with the jumpers in.

I then did the 500 mile head bolt retorque and valve lash adjustment. Seems the lash was too loose on some and a tad tight on others.

I then did a compression test. All four had between 142-151, which is way down from previously (before I blew the last HG) which was at close to 170 on all four.

I also noticed that all four (but mainly 2-4) wouldn't hold pressure. Cylinder 4 seemed to be the worst. After putting some oil in the cylinder and retesting it held a tad better but still not good.

I've always heard that if the oil trick doesn't stabilize things, then the leak must be in the head, right?

Also, what causes all 4 cylinders to drop 20 lbs in compression at the same time?

It seems to be burning oil too, but I'm not totally sure about that yet.
Posted By: Runner-Man

Re: 500 miles since HG replacement - 12/12/10 10:36 PM

About the compression loss: The only way I can imagine a head gasket causing this would be if the head gasket is thicker than the old one. Then the total volume in the combustion chamber would go up, so the compression would go down.

Or, did you clean the pistons off when you removed the head? If so, all that carbon buildup on the pistons will raise compression some; scrape it off and compression goes down.

Lastly, if you set the valves without enough gap, the valves will never close fully, and the engine can't develop compression. You will also burn the valves.

Is power down? Did you rebuild the head when it was off? A leaking valve stem seal could be the reason for oil loss. Look for a puff of blue smoke when you start it, or if you let it idle for a long time and then rev it up. These are indicators of a valve stem seal.

Good Luck, I hope this will help a little.
Posted By: outdoorfan

Re: 500 miles since HG replacement - 12/17/10 01:54 AM

This is my second blown HG. The bottom end of the engine is all stock. The head is EB and only has around 25,000 on it. Everything was perfect before the 2nd blown HG.

Yes, there is a power loss that I can feel. There was no appreciable carbon anywhere due to having been in it and cleaned it not that long ago.

I ordered the standard thickness gasket. I'm not sure, but I doubt the thick one would lower compression by that much.

I carefully set valves.

I'm not driving it much right now, but when I do I'll look for any weird smoke coming from the exhaust.
Posted By: whitetoy

Re: 500 miles since HG replacement - 12/19/10 06:32 AM

Quote
This is my second blown HG. The bottom end of the engine is all stock. The head is EB and only has around 25,000 on it. Everything was perfect before the 2nd blown HG.

Yes, there is a power loss that I can feel. There was no appreciable carbon anywhere due to having been in it and cleaned it not that long ago.

I ordered the standard thickness gasket. I'm not sure, but I doubt the thick one would lower compression by that much.

I carefully set valves.

I'm not driving it much right now, but when I do I'll look for any weird smoke coming from the exhaust.


Seems to me a bad HG or valve would not cause all cylinders to be low in pressure. One possiblity is the timing chain is not installed correctly (crank gear marks and cam gear marks must line up). That would affect all cylinders equally and affect power.
Posted By: outdoorfan

Re: 500 miles since HG replacement - 12/20/10 05:24 PM

I reinstalled everything the correct way, pretty sure. I drove it for the first couple weeks after HG replacement without any troubles. I hadn't checked compression at that point, however.

All of a sudden, one morning when I started it up and drove it I could hear some pinging or valve noise when under load.

I just talked to my wife's cousin, who is a Toyota tech, and he suggested that the rings are going for whatever reason. He suggested that if it's using oil, which I think it is but haven't verified for sure yet, then that oil (when mixed with gas in the combustion chamber) will reduce the fuel octane thereby causing that pinging that I'm hearing. He suggested added some octane booster to see if the pinging goes away. Then the question would be why in the world are the rings all going bad at once? The bottom end is completely stock and has 180,000 or so on it.
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