axelkoup

yes i know this may be my first post on here but ive been on marlin for years, and never really used this forum... im on marlin as Stinky...but anywho...heres my issue:

i got a 94 sr5 p/u, 3.slow, spotless n all the bells n whistles...picked it up for pennies last year with a bad motor last new years...myself n my old man pulled it out n rebuilt it...tore it down to a bare block and sent it toa machine shop for whatever needed fixed, put it all back together and it ran great until around june...

then it started givin me when it would start cold, or after sittin for a while...it progressively got worse all summer...changed the TPS, resistance checked ever single sensor and then some... everything tested great...until yesterday...and now its gotten to the point where it will take 5 mins of cranking over to start...or just turns over long enough to run my red top to the point it cant turn thestarter fast enough....but if it's bump started, it fires right up, still doesnt idle w/o assistance, but once it gets hot, it runs like a raped ape and will start back up alllll day long...

took a compression check on cyl 2 n 4, which showed 35psi, then 3 showed 171psi and 5 showed 50psi...didnt bother with the others since it was a given the heads had to come BACK off...just to make sure, with the valve cover off, and moving each cylinder to tdc, we checked the cam/tappet clearence, which for the intake side was .006-.009??... well, not even a .0025" feeler would fit....and when the cylinder was pressurized the air came right out the intake....so it was proven that there was a serious intake valve problem....but keep in mind, after it got hot, it would run like there wasnt a damn thing wrong with it....

so as of now the heads are at the machine shop, hopefully they'll get to them asap, since im only home from college until next monday....

anyone ever hear of or had this issue before??

Burntricer

correct me if im wrong, does the 3.0 have more then one intake valve?

axelkoup

nope single overhead cam 12v none of the piston/valves touched either...thank God

Green93

I have close to this same problem. I recently had the whole engine redone, including the heads. There is now 10,000kms on the rebuild. I have been trying to find the cause of a bad idle(rough) and have replaced and tested most of the sensors. I did a compression test and found 2 cylinders at approx 40psi. Another one was very low at 75psi and the other 3 were better but not the greatest.

She lacks power cold but when warm goes great, although still idles rough. I'm hoping that my problem is just a valve adjustment. As the new engine wears in the valves hit the valve seats, setting them farther into the head. When this happens the clearance on your cams goes way down. Which is probably why you cant even get a .0025 feeler gauge in there. Compression is lower because the valve is always held open slightly. When you're on the throttle the piston is compressing the mixture so much faster that it doesn't leak out as much, compared to just turning the engine over with the starter.

I have my fingers crossed that this is my problem, I don't want to take the heads off again, that means new head gaskets and head bolts.

Jason

axelkoup

well its great to see someone else had the same problem as me...cuz i seem to have the most random happen to me and people just give me a wierd look and say, its gotta be your driving style... haha this time theres no excuse, just somethin moved in the heads and when its hot a clearance is made up for and it runs fine...im hopin the machine shop gets to them today, so i can get em back tonight or friday n get it together fri/sat, cuz i head back across the state to college on sunday...

TNRabbit

Weak or broken valve springs?

axelkoup

nope, if they were weak or broken, the lifter tappet would not be pinned against the cam...

im assuming the valve springs were either too tight and tulip'ed the end of the valves or the valve seats.... just wondering if anyone else had the problem...and if its gonna happen another 6k miles down the road...

Green93

Well, make sure you post up what the machine shop finds out. I am dreading this, and if I don't end up working 7 days this week I'll be diving in.

Thanks,
Jason

Bigblock

The valve shims are too thick.Either buy thinner ones from the dealer or take to a machine shop and mill off.Those shims are how you adjust the CL and are not all the same.
Bigblock

mistreatedtoys

I agree the valve shims are to thick. I bought a 4runner with a stuck valve on a rebuilt engine. It seems after break in the clearences change. There is usally a chart in the manuals about what shim to use however you will find out when requesting these at the dealer they act as if you are the only one ever to mess with these. Once you can spot the problem and know the repair there are many trucks out there for the taking very cheap.

axelkoup

ya, thats what im hopin it is, because the machine shop told us thats how they set the valves to begin with, just grind em till the clearance is right...

im still boggled at how when its HOT the tolerances get loose, not tight...i dunno...i just want the damn thing to run

Bigblock

The reason they are tight now should boggle your mind.The cam and shim dont wear as much as the valve face and the seat in the cyl head.
Bigblock

axelkoup

welp, 1000 miles later, and its done it again.... machine shop said maybe the heads have had too many valve jobs done on them....this will be the third, and im almost POSITIVE the only thing they did the second time was just change the valves...

i think their full of and their either using cheapy valves and/or too tight of springs...

anyone have other ideas??