? on selecting new hydraulic lifters

Chris611

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I have a '96 Merc 350 4 bbl. Last season I had a problem when I ran WOT (4600) for extended peoriods. The engine would slow after about a minute and then it sounded different, more hollow and louder. After shutting off for a minute, it would be okay until WOT. So I just refrained from running WOT towards the end of last season. I would like to fix this spring. I have checked oil level, changed oil weights, tried SEAFOAM, all with no success. My thought now is it may have been a hydraulic lifter pumping-up and holding the valves on one or more cylinders open. I was going to replace them this spring. I was planning on using CRANE "Anti-pump up" lifters. I think $100 a set. Will these work and how easy are they to change? Let me know your thoughts and experiences.<br /><br />Thanks<br />CP
 

tommays

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Re: ? on selecting new hydraulic lifters

cp<br /><br />i would think a problem in the fuel system would be a much better guess ,like a clog in the tank vent or anti siphon valve,fuel filters amoung many things<br /><br />the lifters would be pretty clackey and would not self repiar that fast<br /><br />tommays
 

Chris611

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Re: ? on selecting new hydraulic lifters

The hollow sound doesn't sound like an engine running out of gas, there is definitely some "chattering" in the engine. Once it starts losing power and begins to make the noise, I pull the throttle back and let it idle and you can hear the clanking escpecially on the right side of the eninge. It just sounds like something metal being struck. I did convert from the 2bbl to the 4 bbl. Unfortunately I didn't have the boat long enought with the 2bbl to know if it acted the same way. <br /><br />Thanks<br />Chris
 

onebadc10

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Re: ? on selecting new hydraulic lifters

cp611<br />The anti pumpups only give you more vaccum at low rpms. That is not your problem because you would be floating the valves and getting a backfire through the carb.I think you have a fuel problem. <br />onebadcamaro
 

Bondo

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Re: ? on selecting new hydraulic lifters

when I ran WOT (4600) for extended peoriods.
I'd Think That is the Root Issue...................<br /><br />That's Not the SBC you're going to find in a NASCAR......................<br /><br />Actually, That "Converted" 5.7l is ALOT Closer to the 350 that you'd find in Grandma's Car .................
 

Chris611

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Re: ? on selecting new hydraulic lifters

Good point Bondo. I agree that these engines get used very different from auto engines. And like anything else mechanical, if something is going to go wrong or is getting worn out, it will show up when you push the engine. I'm not looking to be able to run the engine at WOT for hours on end, but a nice 2-3 minute blast down the river would be nice. I thought that the marine version engines had heavier cranks, rods, etc... to handle the higher sustained RPM's? How many of you run the engines at WOT and for how long, just curious.<br /><br />Thanks for the replies<br /><br />CP
 

onebadc10

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Re: ? on selecting new hydraulic lifters

Chris<br />With the noise it is not a fuel problem. You are going to have to remove a valve cover and look at your valve train. <br />Tony
 

Dunaruna

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Re: ? on selecting new hydraulic lifters

What side of the engine is the fuel pump?
 

Don S

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Re: ? on selecting new hydraulic lifters

You should be able to run your engine at WOT all day without problems, it won't last as long, but you can do it.<br />Did you by any chance change over from dino oil to synthetic? I've seen engines that it won't work on.<br />You may also have a timing advance problem, check to see if you are getting full advance at higher rpm.
 

TilliamWe

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Re: ? on selecting new hydraulic lifters

Does this boat have open exhaust, by any chance?<br />This may sound stupid, but hear me out. We had an 84 model boat that we put thru hull exhaust on. Well, it ran perfectly at all speeds & rpm, except at WOT. If you ran it WOT for about a minute (not very long I know), the pitch of the exhaust change noticably. <br />Well in our case, it was the impeller in the drive that could't pump, and the water would stop coming out the exhaust (hence the change in exhaust sound). Now, if we kept running it, the motor would have gotten hot, but we never allowed this to happen.<br />Is there any chance that this is what's happening to this engine???
 

Chris611

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Re: ? on selecting new hydraulic lifters

The boat does not have any open exhaust (sometimes wish it did, it would be cool to make some noise every once and awhile!) I am still using non-synthetic oil, originally the mech put 25W-50 Merc oil in it. I tried 20W-40 HD Quaker state to see if it was an oil delivery/viscocity problem. I would like to go back to the merc oil or equivalent before this summer. Keep the suggestions coming, I am making a list for when I get the boat out of storage...the time is getting near...although its snowing today.<br /><br />CP
 

bomar76

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Re: ? on selecting new hydraulic lifters

Just a wild SWAG....but is there any chance your carb is leaning out on you at extended WOT runs?<br />I don't think a lifter is your problem...a sticking valve would cause other symptoms.<br /><br />Or this brainstorm....<br />Are you absolutley sure the oil isn't over filled (dipsticks can be wrong)? Too much oil would possible aerate (from hitting the crank)and cause wierd problems. Immediatly after a WOT run where this happens, pull the dipstick and check for aerated oil.<br /><br />Also...runiing at WOT at a high angle of attack (bow up) would potetially cause aeration problems.<br /><br />Just guesses.
 

rayjay

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Re: ? on selecting new hydraulic lifters

4600 rpm is nothing for a SBC. This motor would thrive on a diet of 6000 rpm shift points in a bracket car. You can adjust the lifter you have. With the engine running back them off one at a time until the rocker starts to clack, then tighten the nut until the rocker quiets down and then tighten the nut another 1/4 or 1/2 turn. <br /><br />You can't just change the lifters anyway. You have to replace the cam and lifters together. They wear as a set and if you replace one without the other you will most likely have rapid wear.<br /><br />Was there a bunch of crud in the engine when you had the intake and valve covers off ?
 

tommays

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Re: ? on selecting new hydraulic lifters

cp<br /><br />(Last season I had a problem when I ran WOT (4600) for extended peoriods. The engine would slow after about a minute) <br /><br />you have me conufsed you start out saying after long periods of WOT and then say that it happpens after 1 min <br /><br />i think it would help if your more clear on how long it takes for the problem to happen<br /><br /><br />tommays
 

KaGee

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Re: ? on selecting new hydraulic lifters

Originally posted by rayjay:<br /> 4600 rpm is nothing for a SBC. This motor would thrive on a diet of 6000 rpm
Note to self: Never by a used car or boat from this guy<br /><br />
You can't just change the lifters anyway. You have to replace the cam and lifters together.
OK, that's a new one. I have never heard that anywhere. <br /><br />Now lifters, push rods and rocker arms I'd go for.
 

Chris611

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Re: ? on selecting new hydraulic lifters

tommays, I should have been more clear. By extended periods, I am refering to 1-3 minutes. The first time I noticed it, I probably ran for 2-3 minutes on the way back to the boat launch. I should have probably not used "extended period"<br /><br />Thanks<br />CP
 

Boatist

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Re: ? on selecting new hydraulic lifters

You can guess and throw parts at it all year and not fix it. I think you will find problem much faster if your start running some tests.<br /><br />To start with I would put in a T between your fuel pump and and carb and hook up a fuel pressure gague. I would also hook up a timing light and a Dwell meter.<br />Then I would go for a run and note my fuel pressure at cruseing speed. also note position of timing mark and dwell reading. ON your dash check water temperature and oil pressure.<br /><br />Then open it up and note all the same. A change in fuel pressure or oil pressure will give you a big clue. Also a change in water temperature. The timing will will change some but not a lot from 3000 to 4600 rpms. The Dwell should stay the same.<br /><br />Another thing I would do is change the oil and carefully messure how much oil you get out of it. It could be the oil dip stick has slipped and you do not have enough oil in the engine. Compare how much oil you get out of it to the spec for your engine.<br /><br />I can not see it being a valve lifter problem.<br /> <br />If you want to keep guessing here is some more.<br /><br />It could be a oil starviation problem. At WOT you could have a loose main spilling lots of oil when under torque and no oil left for the lifters cam and rockers. The drain back holes in the head may be somewhat blocked so all the oil is in the head and the oil pump has no oil to pump to the bearings and lifters.<br /><br />You changed to a 4 barrel carburetor so maybe the front two barrels work fine but the float for the back two barrels is stuck or letting in fuel very slow. When You run at low rpms the back two barrels are closed so it runs fine. When your go to wot all 4 barrels open but you very soon use up any fuel for the back two barrels so now the back two barrel are letting in more air but no fuel and you are running very lean.<br /><br />You changed the Carburetor to a 4 barrel but can the fuel pump supply enough fuel for all barrels at wot.<br /><br />You changed to a 4 barrel but did you change to a larger back flame arester, also is it clean so you can get lots of air.<br /><br />Have your tried removing your gas cap to make sure it does not have a blocked fuel vent pipe.<br /><br />Could the points spring be installed wrong so at high rpms the spring can not close the points fast enough and the points float and your spark becomes weak and at the wrong time.<br /><br />Is the motor heating up because the exhaust manifold and riser are blocked and can not get enough water flow to keep the engine cool.
 

jimmythekid

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Re: ? on selecting new hydraulic lifters

at least do a leak down test first!!!!!!!!!!<br /><br />If you think a lifter is bad, it probly isn't. Oftentimes its another worn part (or two) that the lifter can't make up for. BTW whats the oil pressure? <br />If it turns out that ANY thing worn out mechanically inside the engine, overhaul the whole thing, <br />you will either be GLAD that you did or SORRY that you did not..<br /><br />4600 RPM all day?<br /><br />did it get hot? At all???<br /><br />when is the last time it had FUEL FILTERS?<br /><br />does the engine make noise? AT ALL????<br /><br />Do you think (know) if you damaged the engine?<br /><br />4600 RPMS SOULDN'T HURT A REAL CHEVY, but anything can happen.
 

trog100

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Re: ? on selecting new hydraulic lifters

oh well.. i nearly made the first answer in tbis thread then thought better of it.. he he<br /><br />my comment would have been.. i think u are chasing ghosts with the "anti pump up" lifter idea.. but i really aint got the faintist idea of what could be really causing your problem..<br /><br />after reading thru this thread i think i would have been about right.. he he..<br /><br /><br />trog100
 

John_S

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Re: ? on selecting new hydraulic lifters

CP611,<br />JMHO, anti-pump up would be just throwing money at this issue.<br /><br />Of course, the last thing you changed is always suspect. Let us know what intake, carb, and flame arrestor you went to, and if you made any ignition changes. Also, did you need to change any jets/metering rods/etc to have it run correctly for your engine? Did you check the carb calibration?<br /><br />Assuming your boat is winterized, and it is not stored in heated garage, you will be waiting till spring tune-up before being able to work on it.<br /><br />It would be nice to know what the plugs looked like after this happened. Most likely they will have fogging oil on them now, but might give some clues. Before heading out this spring, do a tune-up including new rotor, cap, and plugs. Do the compression and leak down, if for nothing else piece of mind, and capture of historical data. Time it and set mixture and idle to factory specs. You would be able to do some other testing while engine running on muffs, such as a vacuum leak check. <br /><br />At least you will be ready to check and do in water testing, the first time out. If it still happens, the first thing I would do is examine plugs after this happened. Should be able to tell if you are running rich or lean or if this is something unique to one cylinder, etc.
 
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