Please Help..worse case/not happy
- Thread starter dwhiskie
- Start date
Pull all the spark plugs out and turn the engine using a 15/16" socket on the harmonic balancer. As you turn, notice any changes in the force required to turn the crank. If you find the force increases dramatically at any one spot, stop turning. This is an indication of interference inside the engine.
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading.Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 psi. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading.Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 psi. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.
Michael Yount
Mustang Master
If it broke at 6 grand, you almost certainly have valve/pushrod damage in multiple cylinders. You may have more significant piston/cylinder head damage. Remember, at that engine speed, the piston is reaching TDC 100 times EVERY SECOND. Even the quickest of shut downs has stuff getting hammered when the crank is disconnected from the cam. If it were mine, I wouldn't bother with all the compression/leak down tests -- I'd just go ahead and pull the heads.
bill302
Active Member
first i would do as jrichker posted in his thread above that i copied into this thread below turn crank and check for binding just in case theres a broke valve and usually you can feel if theres damage but in some cases you have to know what to feel for...
Pull all the spark plugs out and turn the engine using a 15/16" socket on the harmonic balancer. As you turn, notice any changes in the force required to turn the crank. If you find the force increases dramatically at any one spot, stop turning. This is an indication of interference inside the engine.
to run compression test....
Screw the gauge into cylinder 1 and rest it somewhere you can see the dial while you crank the engine. Open the throttle fully either by pressing the accelerator or wedging the linkage open under the bonnet. If the throttle isn't open then air can't get into the cylinder and the readings will be far too low. Crank the engine until the gauge stops rising and count the revolutions while you do so. It should normally take no more than 10 engine revolutions (5 compression cycles) to get a full reading then go to the next cylinder and repeatuntil you have completed all cylinders or recieved 0 psi..if you run the compression test you can run it cold and if you have valve damage it will read very low compression probably 0 psi... just write down compression readings in thread...
Pull all the spark plugs out and turn the engine using a 15/16" socket on the harmonic balancer. As you turn, notice any changes in the force required to turn the crank. If you find the force increases dramatically at any one spot, stop turning. This is an indication of interference inside the engine.
to run compression test....
Screw the gauge into cylinder 1 and rest it somewhere you can see the dial while you crank the engine. Open the throttle fully either by pressing the accelerator or wedging the linkage open under the bonnet. If the throttle isn't open then air can't get into the cylinder and the readings will be far too low. Crank the engine until the gauge stops rising and count the revolutions while you do so. It should normally take no more than 10 engine revolutions (5 compression cycles) to get a full reading then go to the next cylinder and repeatuntil you have completed all cylinders or recieved 0 psi..if you run the compression test you can run it cold and if you have valve damage it will read very low compression probably 0 psi... just write down compression readings in thread...
Im just going to pull the heads and be done with it I guess. I usually dont get lucky and have something simple so that being said I will just take my time and get it done right the first time. How much do you think it might run me($) to get the heads reworked and whats a good head gasket that will hold up to boost? Also I need a balancer, Any ideas for a good one of those? Money is some what of an issue. Thanks
Michael Yount
Mustang Master
If that thing has been running under boost, and you're serious about keeping it together, I'd take a good close look at the block as well. It may well be that the block is 'flexing' (as in about to split down the middle) and that's what caused the timing chain to break. No sense spending good money on the other bits if the block isn't gonna hang on any more. And to bring it back to the original question you posted - that's gonna be your worst case scenario. With the numbers you're making, you're on borrowed time with a stock block.
Michael Yount
Mustang Master
Michael Yount
Mustang Master
You need more block strength if you're gonna assure longevity with boost-induced HP levels. More block strength means Dart, World Products - something like that. Most feel the Motorsport blocks are much better than a late model stock block. Some insist the Mexican-cast stock blocks have more beef in them than the other stock blocks. You'll have to decide for yourself.
If you're going back to N.A. with your current build and your current block isn't harmed -- you don't need to upgrade. Unfortunately, the only way to be certain about the integrity of your current block is to have it tested (mag, ultrasonic, etc.) at the machine shop.
If you're going back to N.A. with your current build and your current block isn't harmed -- you don't need to upgrade. Unfortunately, the only way to be certain about the integrity of your current block is to have it tested (mag, ultrasonic, etc.) at the machine shop.
bill302
Active Member
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