whippled 8.1l build

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

Wound-for-Sound

Pushrod length okay? If it wont start check the basics. Fuel and spark. If you are getting both we are down to cam timing, as engine timing is in the tune.

whippled 8.1l build

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

Wound-for-Sound

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.

whippled 8.1l build

thought about that but for 175 the machine shop said they do both the vales and heads and ill know its perfict

Wound-for-Sound

But what if it isn't your heads and valves? your back to square one?

whippled 8.1l build

correct......
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

Wound-for-Sound

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.

whippled 8.1l build

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

willizm

iTrader: (10)

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

whippled 8.1l build

yea i checked both. sputtered when i was first trying to start it but then i found out i had bad grounds.. paint stoped them from getting a good ground. once i fixed that it didnt sounds like it was even back firing. this is when i started checking compression. now all i can figure out is the valves. totaly unhooking rockers and putting the piston at its lowest point and still low compression, about 60psi on the bad cylinders.

Krom

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)

whippled 8.1l build

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.

whippled 8.1l build

pulled the heads.. yup several valves wernt completly sealed. about 1/4 inch on the valve waasnt sealed by just enough to not work

whippled 8.1l build

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

xx_ED_xx

iTrader: (17)

there was a redone set on ebay for 500 bucks, I got a set heading my way but they are spoken for

xx_ED_xx

iTrader: (17)

whats wrong with the other set besides the mileage?

whippled 8.1l build

nothing they were just dirty and not ported.. at the machine shop. also getting new springgs compcams 911-16

Wound-for-Sound

So you have a set? I have two sets sittin here if you need some

whippled 8.1l build

i had my running motor that broke a piston from running lean and a spare set.. so yea im good untill i decide to make another spare motor