ugh 8.1l problems
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From: thurmont, maryland
ugh 8.1l problems ok i have a 03 8.1l fresh rebuild 60 over. comp cams blower cam 4degree built in advance. front mount intercooler, whippled. cant get the damn thing to start..
cranked and cranked and cranked.. had low voltage and ended up being bad ground that i fixed. now its just cranking. low compression as in its either my gauge or it has no oil on the rings now and putting trans oil in the cyliners helps. but im still confused because to get the most compression i halfto back the damn rocker arm bolts off untill theyy are way to lose....
HELP
cranked and cranked and cranked.. had low voltage and ended up being bad ground that i fixed. now its just cranking. low compression as in its either my gauge or it has no oil on the rings now and putting trans oil in the cyliners helps. but im still confused because to get the most compression i halfto back the damn rocker arm bolts off untill theyy are way to lose....
HELP
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From: thurmont, maryland
so heres what we have found by checking compression and our conclusion is that its the valves not being seated good enough. used valve grinding compound and it just doesnt seem to have worked. machine shop here i come again
Staging Lane
Joined: May 2012
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From: Worthington, IN
If you pull them off. Pop a few valves, paint them with a magic marker or something along with the seat. Put lapping compound on the valve and lap it in. Pull valve out and look at where its sealing.
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From: thurmont, maryland
checked compression on cylinders with rocers in place and with them lose. made a bigger differance lose then not in place at all. all we can asume is that they arnt sealing at all. number 4 is 160psi number 8 is 110-120.. 4-6 are both 30-60. number 1 is 60-100 depending on oil in the cylinder..
oil in the cylinder makes a differance because i had already cranked the motor over for a while before finding out that i had 2 bad MAIN ground wires.
havent tested psi on 3-5-7
asuming there the same as the other side but due to the fact 1 isnt getting good psi the head hasto come off anyway.
valves have 250k on them from original motor and are in a new set of heads i had here at the house to make a spare motor but ended up needing to use them before havving a chance to fully finish the motor
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Staging Lane
Joined: May 2012
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From: Worthington, IN
What do the numbers go to with oil in the cylinders? Oil in the cylinder increasing your compression just means you've wiped all the oil off your cylinder walls before everything broke in to seal the rings. I still think your on the right track, but not 100% sure that is your entire problem.
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From: thurmont, maryland
yea i was some what concerned about having wiped out the rings myself but the motor has not yet fired. acording to other info i have seen it says that if you have excessive cranking without it starting then you can wash all of the oil out of the cylinders because of the extra fuel in the cylinders so there for you halfto add oil to get everything to move/ seal untill it starts.
compression went up in the 1-4 cylinders but only by about 10psi
compression went up in the 1-4 cylinders but only by about 10psi
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From: Joliet,IL and Las Vegas 50/50
does it sputter at all when cranking? Dumb question but did you check simple things like cam and crank position sensors. I got caught up with the crank sensor not being plugged in once. Damn near ripped my hair out trying to figure out why until I found it. Blonde moment
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From: thurmont, maryland
does it sputter at all when cranking? Dumb question but did you check simple things like cam and crank position sensors. I got caught up with the crank sensor not being plugged in once. Damn near ripped my hair out trying to figure out why until I found it. Blonde moment
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If your set on pulling the heads, at least do a leak down test first, you can make your own tester, or buy one from harbor freight for cheap, with the rockers loose it will tell you for sure if a valve or valves are leaking (and which ones if you listen for the air)
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From: thurmont, maryland
yea the inlaw and i were thinking of doing the same thing.. the compression tester i have has a quick connect the we can connect to. would tell me if its for sure the valve seats. ill bet it is since the valves have 250k on them and the heads i used arnt the same as the ones the valves were in.
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From: thurmont, maryland
OMFG wasnt expecting the call from the machine shop today saying "well we cleaned the heads and well your not gonna belive it but". yes what am i not gonna belive "They are both cracked all the way to the combustion chamber". SON OF A......... bought those heads 2 years ago so i cant even go after the person who sold them to me
