12-01-2012, 03:47 PM
while we're still touching the subject on engines......... Today, well yesterday actually, I had a bit of a brain fart.
Here's the story.
After picking up the old Humber Super Snipe a week ago, I've been going through it with a fine toothed comb to find and fix or replace everything needed so I can get it through registration and be able to drive it.
I pulled the spark plugs and found one was cracked through the ceramic, upon removal a few pieces dropped into the hole in whoch the plug is housed. Not into the bore, just the hole which is about 4-5 inches deep. The Humber uses an engine which is basically one of the first Hemi style designs so the plugs are top and center of the head sunk deep below the surface of the rocker cover.
Using a screw driver with grease on the end, I was able to fish all the pieces out, a very time consuming, careful process as you don't want ceramic shards to find their way into the bore.
I then fitted the new spark plugs and fired it up to find it was now missing and running a little rough. I started pulling leads off one by one starting at no.6 and when I pulled no.4 there was no change in engine tone. Right, that was the offending cylinder.
I pulled that plug, checked for spark, spark was strong. Thinking the worst, I grabbed the compression tester and checked compression on that cylinder. The reading I got was half of what it should be! Figuring the head was going to have to come off I tracked down a head gasket in the U.K. for $185 as I could not find one here in Australia. The next cheapest set I found was in New Zealand which was $220 + postage!
Quickly ordered and paid for it then remembered I hadn't checked the other cylinders for compression. One by one I checked the others and they all came out within a few PSI of no.4.
Somethings not right here... it seems to only be missing on the one cylinder.... got even compression and strong spark....
In my carelessness I didn't number the leads, Being a straight 6 and with all leads running from the very front of the engine I didn't bother as they were all at a length which meant they'd only suit their respective cylinders..... wrong! no.3 and no.4 are quite close together and I'd swapped them around! Rookie mistake.
I shouldn't have stopped once I pulled no.4 lead, had I pulled no.3, I would have noted it too wasn't firing but I didn't.
I didn't number the leads, I should of.
I didn't check the compression tester. I was curious on it's accuracy so i made a quick adapter and plugged it into the compressor and it displays less than half of what it should. Bought a new tester and retested the compression which all came out within 10psi of what the engine should have, great news.
I now have an un-needed head gasket, a small hole in my pocket and a bruised ego.
At least if/when the head does have to come off, I won't need to wait for a gasket set....
Hope the rant all makes sense!
Here's the story.
After picking up the old Humber Super Snipe a week ago, I've been going through it with a fine toothed comb to find and fix or replace everything needed so I can get it through registration and be able to drive it.
I pulled the spark plugs and found one was cracked through the ceramic, upon removal a few pieces dropped into the hole in whoch the plug is housed. Not into the bore, just the hole which is about 4-5 inches deep. The Humber uses an engine which is basically one of the first Hemi style designs so the plugs are top and center of the head sunk deep below the surface of the rocker cover.
Using a screw driver with grease on the end, I was able to fish all the pieces out, a very time consuming, careful process as you don't want ceramic shards to find their way into the bore.
I then fitted the new spark plugs and fired it up to find it was now missing and running a little rough. I started pulling leads off one by one starting at no.6 and when I pulled no.4 there was no change in engine tone. Right, that was the offending cylinder.
I pulled that plug, checked for spark, spark was strong. Thinking the worst, I grabbed the compression tester and checked compression on that cylinder. The reading I got was half of what it should be! Figuring the head was going to have to come off I tracked down a head gasket in the U.K. for $185 as I could not find one here in Australia. The next cheapest set I found was in New Zealand which was $220 + postage!
Quickly ordered and paid for it then remembered I hadn't checked the other cylinders for compression. One by one I checked the others and they all came out within a few PSI of no.4.
Somethings not right here... it seems to only be missing on the one cylinder.... got even compression and strong spark....
In my carelessness I didn't number the leads, Being a straight 6 and with all leads running from the very front of the engine I didn't bother as they were all at a length which meant they'd only suit their respective cylinders..... wrong! no.3 and no.4 are quite close together and I'd swapped them around! Rookie mistake.
I shouldn't have stopped once I pulled no.4 lead, had I pulled no.3, I would have noted it too wasn't firing but I didn't.
I didn't number the leads, I should of.
I didn't check the compression tester. I was curious on it's accuracy so i made a quick adapter and plugged it into the compressor and it displays less than half of what it should. Bought a new tester and retested the compression which all came out within 10psi of what the engine should have, great news.
I now have an un-needed head gasket, a small hole in my pocket and a bruised ego.
At least if/when the head does have to come off, I won't need to wait for a gasket set....
Hope the rant all makes sense!