Oobyscoot Posted October 25, 2010 Share Posted October 25, 2010 I have another thread running regarding my cylinder head woes, but, further to that I a a little confused.Did a compression test before pulling the head, got readings of 150 - 155 psi, I took this to be good for a 30 odd year old mmotor. Anyway removing the head for other issues presented me with this little bit of confusion.I had removed all manifolds and such from the head, rocker gear out and pushrods safely out of the way, all head studs removed, waterpump off and out of the way, nothing holding it in, but I could not shift it, no, wont budge, stuck fast.No in the past in this situation, (with an OHV engine) I just put the spark plugs back in and crank it over a few times, so I did this expecting the head to pop off, nothing, not a thing. I tried by hand and found I could turn the engine over just by rotating the front pulley with my hand, How could I do this with the spark plugs in ??????As I turned it, I could hear the air coming trough the exhaust ports even though the valves were closed. How can this be if the compression readings were good?Is there anything I am nmissing? I have never been able to turn an engine past compression with this method before, its got me very confused............ Link to comment Share on other sites More sharing options...
piman Posted October 25, 2010 Share Posted October 25, 2010 Hello Oobyscoot, I suspect that the leakage is generally all over as there is no pressure on the head gasket?The head must have lifted just a bit.I'm very surprised that having all the studs out that it won't come off, there's nothing to hold it?You could try the rope into the spark plug holes and turn the engine over, the bulk of the rope pushes the head up?Alec Link to comment Share on other sites More sharing options...
GT6 M Posted October 25, 2010 Share Posted October 25, 2010 Are you pulling a face,(think)(whistle)(think)(whistle)cos if ye arn,t then you no trying hard enough. ;)can see why it wont come off if o the studs are oot, they are all out are they !!! Link to comment Share on other sites More sharing options...
Tom2000 Posted October 25, 2010 Share Posted October 25, 2010 I found my head wouldn't come off in this situation due to a number of washers that were carbonised into the top of the head (found under where each nut came off). I chipped at these with thin screw driver/sharp pin. Once they were off the head came off fine. Link to comment Share on other sites More sharing options...
James Posted October 25, 2010 Share Posted October 25, 2010 Remove the studs if you can - it's much easier to get off with them out. Link to comment Share on other sites More sharing options...
piman Posted October 25, 2010 Share Posted October 25, 2010 Hello Tom\James, er, read the first post again, all the studs are out!Alec Link to comment Share on other sites More sharing options...
Nick Jones Posted October 25, 2010 Share Posted October 25, 2010 Just needs more violence then :P Big hammer and a block of wood (or just a big block of wood) hitting across and slightly upward on the ledge above the spark plugs works for me. No bashing the head directly with a metal hammer though!Hearing gas leak past the exhaust valves (or the inlets for that matter) when you turn it by hand can be considered normal on an engine that has done any work. Even at cranking speed this becomes a very small proportion and doesn't affect compression all that much. You won't hear a leak that affects compression significantly when turning by hand 'cause you don't build enough pressure to make it hiss......Nick Link to comment Share on other sites More sharing options...
JohnD Posted October 25, 2010 Share Posted October 25, 2010 String/small rope trick.Stuff it in via one spark plug hole until the bore is full with the piston about halfway up, then turn towards TDC.Sash cord (for sash windows) is good - right diameter and quite dense.You can repeat this in any cylinder, to work it upwards.JOhn Link to comment Share on other sites More sharing options...
drofgum Posted October 26, 2010 Share Posted October 26, 2010 Oobyscoot,Yes, the string / small rope trick is the next thing to try. You can even put a small rope in both 1 and 4 to lift both ends at once.The ability to turn the engine by hand with the plugs in tells you that you have broken the compression seal, and does not speak highly of the condition of the rings; they should make the engine harder to turn than that. Good luck, Paul Link to comment Share on other sites More sharing options...
Oobyscoot Posted October 26, 2010 Author Share Posted October 26, 2010 Cheers guys, Head came off with a rubber mallet.drofgum - rings are shafted, see my engine goo post. Link to comment Share on other sites More sharing options...
.thumb.jpeg.b15b81ef10abeea1c3039ae03c4a9f3a.jpeg)
Recommended Posts
Archived
This topic is now archived and is closed to further replies.