Hydraulic Lifters Bleed Down Time

[twwmm]

Hi There<br />Though I would post this a new topic as it could get interesting.<br />Sencario Chrylser 318 not getting full revs see other post.<br />Wont go over 3000rpm under load<br />Pressures OK Carbys OK Advance OK Fuel OK etc, but have found that the hyd lifters have around 6mm lift using a dial guage on the rocker, they then bleed down to about 3mm over 6 seconds, ??????.<br /><br />Question is is this normal for this motor as all lifters I have seen tend to hold pressure for days-weeks, anyone got any advice???<br /><br />Would be muchly appreciated.<br />Terry<br />

 

[petryshyn]

Re: Hydraulic Lifters Bleed Down Time

hydraulic lifters do bleed down over time. the specs are typically in seconds.....<br /><br />>have you checked the intake manifold vacuum at idle, then at 2500 rpm on both engines?

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

vacume is fine, running out of checks, someone said 3.5lb fuel pressure on bad motor oposed to 1.5 on good motor might be causing flooding.<br /><br />Starting to tear out hair, not much left, cannot find any fault to cause probelm grrrrr.

 

[petryshyn]

Re: Hydraulic Lifters Bleed Down Time

I doubt the fuel pressure issue....<br /><br />What was the vacuum at idle, then at 2500 rpm (no load)?<br /><br />*this will point to camshaft condition, cam timing, exhaust restrictions and ign timing.<br />(very important test)

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

Was no load, timing ok, camshaft timing ???<br />Possible dont know why it would be out but maybe prior owner, should have seen state of things when I bought the boat (yuk). Hmmm wonder how I can check it without removing timing cover, cant I suppose.<br /><br />Thnaks for the advice

 

[petryshyn]

Re: Hydraulic Lifters Bleed Down Time

one more time........<br /><br />>What is the vacuum at idle and then at 2500 rpm? >You say its ok, what is OK?<br />>You say the carb is OK. Did you partially restrict the air intake (using the choke butterfly valve) at WOT under load, to richen mixture? (if RPM increases, this will point to a lean condition)<br />>you say the advance is ok. Did you check maximum "mechanical" advance? How much was it? How did you check it?<br />>Did you check fuel pump pressure and volume? How did you check it?<br /><br />*Valve timing can be checked easily by looking at manifold vacuum. You can also pull a rocker cover and position the crank till you have the center of valve overlap on #1 cylinder.(both rocker arms in center of travel) Then look at the crank timing mark. It should be TDC. Don't forget to center the play of the timing chain. If you have 18"hg at idle or better, cam timing is likely OK.<br /><br />*what carb does it have on it? Is the power circuit working? can you feel it kick in around 5-8"hg"?<br /><br />Lots of factors here. Start off with giving the vacuum at idle, then at 2500rpm with no load....

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

Vacume, dont remember the number but the guage was a professional guage with various indicating regions, idle vacume was in the green as it was at high rpm about middle of the guage, reading was taken using the PCV line which connects directly under the carby to the manifold, there was no indication of timing errors or flucuating needle readings using the guage, all vacume indications appeared normal per documentation used with the vac guage.<br /><br />Have not tried to richen mixture at WOT, but will, have swapped carbs between motors though.<br /><br />Mech adv looked correct per other motors, checked using time light and watched advance move as rpm increased, cant give the actual number but will check closer. Also Mech advance movement in dizy feels correct, adv curve was setup professionly prior to install, will swap dizy between motors as well.<br /><br />Fuel Pres guage was conntected in the line just before carby, checked at idle and wot under load, dont know how to check volume.<br /><br />they have rochester quadrajets, power circuit?<br /><br />Schematic, Thanks for your help, really though id found something with the lifters just seems strange that when you look at the rockers they all look the same height, as if the lifters bleed back to a level point, confirmed by dial guage, I thought if they had 6mm lift they would stay at the height for some time, but they are totally non adjustable so isuppose they may come back quicker that adjustable types. <br /><br />do you think cam timing would have shown on the vac guage? it was steady except when cycling throttle drop then increase back to normal.<br /><br />Thanks again

 

[sho305]

Re: Hydraulic Lifters Bleed Down Time

I had a boat with retarded timing, and it idled faster and was more responsive after cranking it up. You might try changing it, be careful of detonation here, a quick test would do. Or, blip the throttle and see how fast it revs compared to the other motor. Only need to blip it to 3000 or so. Should see/hear difference if timing. Does this rmp difference happen at lower rpm/throttle too, or all the time? Does motor miss or bog or run smooth?<br /><br />You might be able to disable the secondaries on the carbs and run each motor alone to see how big a power difference there is at part throttle? This would also tell if secondaries had a problem. If quadrajets check secondary needles(that move with upper plates on top) for dirt/action. If you can do it safely, you can look in there under load and see fuel coming out and plates opening on their own in the quadrajet. Can also check plugs for bad mixture after running under load a few minutes, shut down quick and pop a plug out on the water, been there many times.<br /><br />Sometimes with bad cam/valves on intake idle is good but can hear slight poping from carb when opening throttle and vacuum is low. Goes away when vacuum is high. The twin BBCs I ran were within 500 rpm of each other at WOT. They were never the same.<br /><br />Some oil treatment might help your compression some, but replacement is key of course.

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

thanks<br />carbs have been swapped between motors, so dont think it is a carb problem, alone the bad motor wont get boat onto the plane and when running both it will turn off course nquicklky at wot indicating the thrust from one is down. Just cant seem to find the fault at the moment but will continue later in the week

 

[DJ]

Re: Hydraulic Lifters Bleed Down Time

Schematic is right, the BEST tool for diagnosing a sick engine is a vacuum guage. It should hold around 18 inches at idle (throttle plates closed). Regardless of the reading, it should be steady.<br /><br />A vacuum guage will tell you if you have a sick valve train, valves/cam/timing. It will also tell you if your ignition timing is way off. It will also tell you if you have induction or exhaust restrictions.<br /><br />Again, you're looking for steady guage readings. Give us some numbers!

 

[petryshyn]

Re: Hydraulic Lifters Bleed Down Time

>does the Quadrajet have a fuel filter built in to the fuel inlet? Have you changed it? Does it have a roll over valve in the filter? Did you remove it?<br /><br />>the relationship of idle vaccum and 2500rpm vacuum will determine if there is an exhaust restriction. (you mentioned the exhaust sounds different) when you do a vacuum reading, don't disconnect PCV. Find a vacuum source fitting elsewhere (there is usually some on carb)<br /><br />>do the engines have a EGR valve? Is it working?<br /><br />>to check fuel pump flow, disconnect fuel line from carb and redirect it into a bottle. Start engine and idle for 30 seconds. Did it pump a pint minimum?

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

Have checked the input filter in carb remember carby have been swapped between motors as well.<br /><br />I will redo vacume test what would you expect for a blocked exhaust?<br /><br />Will do volume test, all good stuf to check again.<br /><br />I will be on bost Thur (now tue night) so me thinks I should:<br /><br />1 Double check fuel supply<br />2 compare fuel volume between motor<br />3 do vacum reading (and record )<br />4 check advance between motors<br />5 swap dizy's between<br />4 do vacume checks and comparisons between motors on load<br /> - used different vac source PCV's are new will swap between motors<br /><br />Sound like vac guage tells all will be pedantic with readings<br /><br />Did I miss anything?<br /><br />Regards

 

[clanton]

Re: Hydraulic Lifters Bleed Down Time

Does it pop back thru the carbuator when engines stalls? what are compressure numbers? Should the fuel pressure be closer to 5/7 lbs. I would run engine with fuel pressure guage connected, when it stalls , if fuel pump, you will see pressure drop.

 

[sho305]

Re: Hydraulic Lifters Bleed Down Time

Not sure how your boat is, but water flow in the exhaust will change tone greatly. <br /><br />Did not see comment it that motor sounds bad-like missing-or if it is low on power at part throttle? Did I miss that?

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

dosn't stall just wont go past 3000, no pop crackle or fiz, other motor fine goes to 4200, nothing obvious

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

sound is just louder, no miss quite bizzare really, just cant seem to find a fault<br />am going to go through list as mentioned. If and when I find the problem I will give a report, hope its not something really dumb.<br />

 

[clanton]

Re: Hydraulic Lifters Bleed Down Time

Tach? You say the rockers all seem even, what do they look like at idle?<br /><br />Back to fuel pressure, I dont have specs for this engine, but I would think it needs 5/7 lbs US<br />to feed a 4 barrel quadrajet.

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

not a tacho problem diffinite can tell by lack of thrust, lifters look ok when running, just suprised at the bleed down from 6 to 3mm in about 6seconds most say this is ok, have to compare to good motor.

 

[twwmm]

Re: Hydraulic Lifters Bleed Down Time

I thought it would need more pressure as well but when I checked the good motor it had 1.5 lb ??? I got excited when the bad one one was 3.5 but lost it when checked the good one.

 

[sho305]

Re: Hydraulic Lifters Bleed Down Time

If the bad engine is louder from the exhaust, you could have a water restriction and overheating. Unless the exhaust is not the same as the other engine, and has different hoses or whatever. I assume the water comes out of your exhaust like most boats.<br /><br />I had to put a strainer on my old I/O water intake after taking apart the pump to get driftwood out of it. Not fun. It got louder and began to steam, but had thru-hull exhaust and was easy to see.<br /><br />You could have a jumped timing chain is the only other thing I can figure. The timing would have been off at some point and been reset. You can put a dial indicator on rocker and check it against the timing indicator to see if valve movement is the same as the other motor. May have to put a degree tape or wheel on the balancer and see what degree a valve starts moving. A chain will jump a tooth then be off 12 degree or more typicaly and the engine will run fine at low rpm with good or better vacuum at idle but no power at high rpm due to retarded cam. Engine will idle very smoothly at very slow idle compared to other engine. If it will idle at say <500rpm smooth and other wont? May be hard to tell as boats have low rpm torque cam anyway. You could rev the engine to say 3000 free and then blip throttle, by hand at carb so you dont go over 4000, to 4000 and see if one is more responsive than the bad one. Slipped timing will make it slow acting at high rpm. Running it can also cause chain failure if so and maybe trash valves as it will slip again. Timing will tend to jump most at idle when cam is jerking around. This would explain exhaust sounding different. Also vacuum should be less than other motor when running free at constant higher rpm, say 3500rpm+. I had a car I could hold WOT and it would run 3500rpm, no faster, running free in neutral.