I recently rebuilt my FJ40 and tried to start it when I noticed I have no compression on cylinders 3 and 5. What could this be? Thanks
No Compression (1 Viewer)
- Thread starter Steamengine
- Start date
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More details on "fj40" and "rebuilt" and " no compression" are in order?
For instance, when you rebuilt your "FJ40", what did you do to the engine? Which engine?
How did you adjust valve clearance?
Etc.
For instance, when you rebuilt your "FJ40", what did you do to the engine? Which engine?
How did you adjust valve clearance?
Etc.
- Thread starter
- #4
As far as I know the engine was completely torn down because one of the pistons shattered. I paid a mechanic to do it but he did a terrible job. It came back to me with a missing head bolt, broken thermostat housing, ect., ect. It sat in my garage for years before I picked it up and realized just how much had not been completed. By that time it was too late to go after the mechanic. I did not adjust the valve clearance. This was done by the mechanic. The motor is an FJ40-110669
- Thread starter
- #5
I pulled the spark plug and put my thumb over plug hole then turn engine over. I did same thing with cylinder 1 and it clearly has compression.
- Thread starter
- #6
The motor is a 1971. Also when I pulled the spark plugs, all of them had carbon build up on them except for the two in cylinders 3 and 5. Those two were the only two that still looked new. Would you recommend I pull the valve cover and check the clearance on those two valves? Also, is it possible that the timing was off and only those two cylinders were damaged?
Yep, X2. If that mechanic work was that crappy then anything could be amiss. Valve adjustment comes to mind but it could be much more complicated than that.
Your FRAME number is FJ40-110669. Your engine no. is stamped on a boss just above the starter, and below the side cover, and should be
F-35XXXX or F-36XXXX or somewhere in that range. At this point, it's likely trivia, but good to know when you have to do work.
First step is to get a copy of the Factory Service Manual for your engine. There are pdf copies on this website.
?Would you recommend I pull the valve cover and check the clearance on those two valves?
F-35XXXX or F-36XXXX or somewhere in that range. At this point, it's likely trivia, but good to know when you have to do work.
First step is to get a copy of the Factory Service Manual for your engine. There are pdf copies on this website.
?Would you recommend I pull the valve cover and check the clearance on those two valves?
Regarding valves, I would look up the valve adjustment instructions in the FSM, and check to see how your valves are operating.
I would do this BEFORE I went any further to remove the head.
Four nuts and the valve cover comes off.
Obviously, compare the action on 1, 2, 4, and 6 to 3 and 5.
?Also, is it possible that the timing was off and only those two cylinders were damaged?I would do this BEFORE I went any further to remove the head.
Four nuts and the valve cover comes off.
Obviously, compare the action on 1, 2, 4, and 6 to 3 and 5.
If four of the six cylinders are timed correctly, the other two are as well. Timing is accomplished by synchronizing the camshaft with the crankshaft, and then installing the distributor correctly and adjusting its position to get the no. 1 cylinder to fire at the right position of the crankshaft. the FSM explains this pretty well.
If you're running on four cyllnders, I can't imagine how timing could be off enough to matter much. Besides, irrespective of timing, If both valves are closed on the compression stroke, regardless of timing, you should have compression. If valves stay open when they're not supposed to, or the piston isn't moving (or is missing
), no compression.
If the valve settings seem okay, when you pull the head you'll be able to see if the pistons are moving when the engine turns.
Report back after each step.
If you're running on four cyllnders, I can't imagine how timing could be off enough to matter much. Besides, irrespective of timing, If both valves are closed on the compression stroke, regardless of timing, you should have compression. If valves stay open when they're not supposed to, or the piston isn't moving (or is missing
), no compression.If the valve settings seem okay, when you pull the head you'll be able to see if the pistons are moving when the engine turns.
Report back after each step.
brian
SILVER Star
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- #12
Thank you all. I will take this advise and look under valve cover. I will let you all know the outcome and post some pics as well. Again thank you.
- Thread starter
- #13
Some Pics.
- Thread starter
- #14
Engine number is F-363353. Thank you 73FJ40.
