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good #'s on compression tests
- Thread starter datant69
- Start date
There are a lot of variables. I think you will be looking for #s that are consistent across all cylinders. IF one cylinder is way off from the rest then you may have a problem. I would think somewhere in the 120-150 range but I have never actually checked a stock car.
SS
SS
compression test
do i have to do anything special other then remove the sparkplug and put in the test plug before i crank it over to get the numbers. I saw on another website that you have to unplug the coil pack or distributor. I know this doesn't have the normal distributor so i wanted to ask before i do this test and screw something up.
do i have to do anything special other then remove the sparkplug and put in the test plug before i crank it over to get the numbers. I saw on another website that you have to unplug the coil pack or distributor. I know this doesn't have the normal distributor so i wanted to ask before i do this test and screw something up.
ALVAROG1983
EVIL GN
- Joined
- Mar 27, 2007
should be ok with coil disconnected and cam sensor..
should be ok with coil disconnected and cam sensor..
If you disconnect the coilpack then the injectors should never fire. You could unplug crank and cam sensors to make doublely sure I guess.
BlackBandit
God loves Buicks!
- Joined
- Mar 29, 2003
Just unplug the orange wire coming off of the battery that goes to the ECM. Then you won't get spark or fuel. Pull all the plugs before you start. Put the compression tester in one hole and floor the gas and crank the engine. Count the number of times the compression "hits" (do maybe 4-5) and then stop, check/write down the number, and move to the next hole. Make sure you count the same number of compression hits on every hole and make sure the gas is floored on every hole.
update
ok guys it's getting 120 on the gauge across the board with the exception of the plug on the front drivers side ( i don't know the numbers so you'll have to bear with me ) and it's reading about 30ish. so i guess it'll be a rebuild or is there a way around it? i wasn't looking forward to a rebuild but if that's the case then so be it. No way to just do that one side or single piston and head? not trying to sound crazy or asking dumb questions but if all the rest are ok i wanted to know if there was anyway other then a complete teardown and rebuild.
ok guys it's getting 120 on the gauge across the board with the exception of the plug on the front drivers side ( i don't know the numbers so you'll have to bear with me ) and it's reading about 30ish. so i guess it'll be a rebuild or is there a way around it? i wasn't looking forward to a rebuild but if that's the case then so be it. No way to just do that one side or single piston and head? not trying to sound crazy or asking dumb questions but if all the rest are ok i wanted to know if there was anyway other then a complete teardown and rebuild.
ALVAROG1983
EVIL GN
- Joined
- Mar 27, 2007
dam thats to bad.
ok guys it's getting 120 on the gauge across the board with the exception of the plug on the front drivers side ( i don't know the numbers so you'll have to bear with me ) and it's reading about 30ish. so i guess it'll be a rebuild or is there a way around it? i wasn't looking forward to a rebuild but if that's the case then so be it. No way to just do that one side or single piston and head? not trying to sound crazy or asking dumb questions but if all the rest are ok i wanted to know if there was anyway other then a complete teardown and rebuild.
Depends on what is wrong with it. It is most likely a headgasket. You could pull just that one head on the side with the low #s but it is just a little more work to do them both and have nice fresh gaskets on both sides.
Sully
what to do
so anyone else think maybe replacing the headgasket could fix this problem. I'm not questioning any responses since the majority of you guys have 99% more time with a car and know more about it then i do. But if i can get away with replacing the headgasket then i'd consider doing that instead of a complete rebuild. I can do a complete rebuild or should i say pay someone to do it but i'd like to have it longer before it comes to rebuilding it before i have to drop another 2k or more to do the work. Anyone else have any luck replacing the headgasket and getting the blowby to stop? I'm new to this and don't know alot about interior engine work. But this may start my experiance on this.
so anyone else think maybe replacing the headgasket could fix this problem. I'm not questioning any responses since the majority of you guys have 99% more time with a car and know more about it then i do. But if i can get away with replacing the headgasket then i'd consider doing that instead of a complete rebuild. I can do a complete rebuild or should i say pay someone to do it but i'd like to have it longer before it comes to rebuilding it before i have to drop another 2k or more to do the work. Anyone else have any luck replacing the headgasket and getting the blowby to stop? I'm new to this and don't know alot about interior engine work. But this may start my experiance on this.
BlackBandit
God loves Buicks!
- Joined
- Mar 29, 2003
Pull the head off and see if the gasket is blown. I don't know how you came to be in this position but it seems kinda weird to just assume the need for a rebuild based on one low cylinder.
to rebuild or not to rebuild
i'm not for rebuilding the whole engine, that came up with my bro in law and a few other freinds who have more internal engine exp then i do. If it's just the headgasket then can the head be pulled off and a new gasket be put in ( i know it's not a simple procedure like a thermostat ) because the head has to come off. But if i can get around having to rebuild the whole thing or just replace the drivers side head gasket then i'll be happier then a teenager on prom nite with a sure thing on his arm. A head gasket is more work then i'm knowledgable of in regards to the inside of the engine but i'd take it to a shop and let them do it. If you do one side do you have to necessarily have to do the other? pro's and con's on this? let me know what you guys think.
i'm not for rebuilding the whole engine, that came up with my bro in law and a few other freinds who have more internal engine exp then i do. If it's just the headgasket then can the head be pulled off and a new gasket be put in ( i know it's not a simple procedure like a thermostat ) because the head has to come off. But if i can get around having to rebuild the whole thing or just replace the drivers side head gasket then i'll be happier then a teenager on prom nite with a sure thing on his arm. A head gasket is more work then i'm knowledgable of in regards to the inside of the engine but i'd take it to a shop and let them do it. If you do one side do you have to necessarily have to do the other? pro's and con's on this? let me know what you guys think.
leakdown
no i don't i was going to rent that tool too but the autozone didn't have the chemicals to put in it. So even though i know i have a blown headgasket or it's looking like i have one due to the compression numbers. Would this test really do much other then tell me what i already know about the head gasket. would it let me know of another problem that the compression test doesn't? Just asking because i don't mind doing it, also does anyone have a link to how to do it to our cars? the autozone had some instructions but they seemed vague in a ways that i wasn't sure it was complete or maybe not help me.
no i don't i was going to rent that tool too but the autozone didn't have the chemicals to put in it. So even though i know i have a blown headgasket or it's looking like i have one due to the compression numbers. Would this test really do much other then tell me what i already know about the head gasket. would it let me know of another problem that the compression test doesn't? Just asking because i don't mind doing it, also does anyone have a link to how to do it to our cars? the autozone had some instructions but they seemed vague in a ways that i wasn't sure it was complete or maybe not help me.
Do you have a cylinder leak down tester available? If so perform a leak down test to see what the problem is before tearing the motor down.
X2 on the leakdown test.
Had somewhat of a similar problem..turned out that a chunk of the exhaust valve was missing when I did my leakdown test. Bought a set of heads and threw it back together. Do a search on the board on how to make your own leak down tester, that's what I did
head job prices
what would be a reasonable price on getting the head gasket redone if this is what needs to be done. I don't have a leak down tester but i will tomorrow and will have the info tomorrow on this if the weather allows. trying to deal with this and my stepson and sons graduation are making my schedule hectic.
what would be a reasonable price on getting the head gasket redone if this is what needs to be done. I don't have a leak down tester but i will tomorrow and will have the info tomorrow on this if the weather allows. trying to deal with this and my stepson and sons graduation are making my schedule hectic.
The tool you speak of is a engine block tester. It uses a chemical that changes color when it reacts with emissions from the engine that are leaking into the cooling system. A cylinder leakage tester injects regulated shop air through the spark plug while the cylinder is at top dead center (TDC). There are multiple items that could be causing that low compression in that particular cylinder that you can determine with a CLT (Cylinder Leakage Tester).
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