1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

You could also have a stuck tappet (over tightening the lifters). How is the oil? Has it been change regularly. Loosen off that lifter so you can hear it tap and maybe the tappet will loosen off if your lucky. Wouldn't hurt to put in a pint of Duralube.
http://www.youtube.com/watch?v=lorANZ1Tptw

 

[coopin87]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Don,
How do I bottom out the lifter? Hit push rod with hammer? Not sure how to make sure. Want to verify its came loan before pulling it.

 

[coopin87]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

You could also have a stuck tappet (over tightening the lifters). How is the oil? Has it been change regularly. Loosen off that lifter so you can hear it tap and maybe the tappet will loosen off if your lucky. Wouldn't hurt to put in a pint of Duralube.
http://www.youtube.com/watch?v=lorANZ1Tptw

Ok so just got losses the nut up and let it run for a bit? Oil was just changed not sure what duration lube is. It does seen to be pushing oil alot better now after adjustment.

 

[Pete104]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Does the pushrod/rocker arm appear to be moving as much as the others?

Stop counting the threads, it means nothing & will only confuse you!
With all do respect, a person blind folded can do what you are trying to get accomplished.

 

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Ok so just got losses the nut up and let it run for a bit? Oil was just changed not sure what duration lube is. It does seen to be pushing oil alot better now after adjustment.

I read your previous posts. What grade of oil are you using? You should be using a thinner oil if your having problems getting oil up to lifters. Your video oil pressure looks ok at idle. Try 10w 30 with a pint of Duralube to get into the journals and the tappets. Make sure you wear eye protection. You can always change again later. She must have been siting for a few years. It is the Chevy 350 ci?
https://www.duralube.com/ 20 bucks but I swear by it. Engine oil treatment.
https://www.duralube.com/Galleries/Small/DURA LUBE ENGINE TREAT -7.0.pdf

 

[joewithaboat]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Guys, if the lifter isn't moving up and down much after the lifter preload is reset... There is only one possible problem. The cam has gone flat. Probably a flat tappet cam and i'm betting the wrong type of oil has been run in it for a while. Forget the miricle oil treatments.

No one believes me when i say you cant run most over the counter oil today on a flat tappet camshaft! It doesnt contain enough ZDDP You need at least 1200ppm It will go flat. All of the cam companies have had warnings out about this for some time now. Compcams has it on there home page currently.

Epa regulations and new emission controls have led the oil companies quit using the anti scuff components that protect a flat tappet cam. They kill catalytic converters. You don't hear a lot about it because most engines have not used flat tappet cams for over 15 years now years now.

You need to pull the intake and inspect the lifter from that hole. It probably looks like this

http://www.corvettefever.com/techarticles/corp_0808_worn_down_engines/photo_03.html

 

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Sorry joewithaboat I don't agree with some of your logic on the over the counter oil treatments. I had bought a 4.3 vortec with 87000 kls and was putting in two liters of oil between oil changes. I used the Duralube and after a year it was good on gas and it did not burn no where near as much oil. Oh the Etest, passed with flying colors. Same with my Chevy inline 6 Mecruiser. Purred like a kitten after it sank.
Were off the subject here, your not going to convince me.

 

[Josh P]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

he is saying no over the counter oil treatmeant will fix a flatened cam lobe, not that they dont work, just not gonna fix the cam lobe. A cheap and good way to get enough zddp, is to run a diesel engine oil, it is plentiful with the addiitive.

 

[joewithaboat]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Sorry joewithaboat I don't agree with some of your logic on the over the counter oil treatments. I had bought a 4.3 vortec with 87000 kls and was putting in two liters of oil between oil changes. I used the Duralube and after a year it was good on gas and it did not burn no where near as much oil. Oh the Etest, passed with flying colors. Same with my Chevy inline 6 Mecruiser. Purred like a kitten after it sank.
Were off the subject here but your not going to convince me.

That's great... you probably had stuck rings from whoever owned it previously neglecting to change the oil regularly. You adding the treatment loosened the rings. No way in he11 its going to fix a flat camshaft !! :facepalm:

 

[joewithaboat]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

he is saying no over the counter oil treatmeant will fix a flatened cam lobe, not that they dont work, just not gonna fix the cam lobe. A cheap and good way to get enough zddp, is to run a diesel engine oil, it is plentiful with the addiitive.

That is true about the zddp levels but it also has other stuff that leaves behind deposits is gas engines. These make hot spots on the combustion chamber and can lead to pre ignition. Lots of good info on the net about it. Google or dogpile is your friend.

 

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

That's great... you probably had stuck rings from whoever owned it previously neglecting to change the oil regularly. You adding the treatment loosened the rings. No way in he11 its going to fix a flat camshaft !! :facepalm:

Ya you hit it right on the nose.
Did you watch the previous video's? Don't know if it was the FPS looked like the lifters were coming back up.
Do you think there is a possibility with the thick oil that that the engine is gummed up and the cam is ok. Usually the cam wears down on all lobes? It should back fire at high RPM revs right?

 

[joewithaboat]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Ya you hit it right on the nose.
Do you think there is a possibility with the thick oil that that the engine is gummed up and the cam is ok. Usually the cam wears down on all lobes? It should back fire at high RPM revs right?

With used engines and inexperienced people working on them (no offense to the op) anything is possible. He said the rocker was moving noticeably less than the rest of the rockers after adjusting it while at operating temp and running. It's got a flat lobe. Ive never seen all the lobes go flat, usually one or two. If it is an exhaust lobe.. yes it will pop at high rpm when it gets really flat.

 

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

For a 100 bucks I would give it a try. coopin87 didn't say he was going to run it in the Atlantic.

 

[tpenfield]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Next steps on this 'project' would be to take a look at the lifter and cam . . . if the lifter is not cupped and the cam lobe looks OK, I'd be replacing the lifter. Oil type/weight is not a make or break on this one.

 

[joewithaboat]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

For a 100 bucks I would give it a try. coopin87 didn't say he was going to run it in the Atlantic.

The $100 would be better spent else where in my opinion. The o/p says he checked/adjusted the preload with it running, the most accurate way. If the lifter is pumping up to allow adjustment it is not likely to be suffering internal damage or sticking. I would bet large sums of money on a flat lobe. He describes the rocker as not moving as much as the others. As far as i remember we didn't get a shot of the #5 cylinder not sure how you are judging its movement. Not that it would matter but to address your concern, he was using the proper weight oil for the engine so that's not it. Its time to start tearing into it.

Note to the op, if the lifter is badly worn, they sometimes mushroom and its best to try and remove them through the bottom of the bore rather than force them up through the top. You can scar the lifter bore.

 

[riptorn]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Ya I agree. I was just trying to be optimistic I guess. I thought those old 350's were work horses .

 

[Bondo]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Ayuh,... Just for the simple fact the rockers were screwed down Tight, 'n not really Adjusted at All,....


I'm goin' with the wiped out cam lobe.....

No oil in the world is gonna beat a 3/8s nut, torqued TIGHT...

 

[coopin87]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Does the pushrod/rocker arm appear to be moving as much as the others?

Stop counting the threads, it means nothing & will only confuse you!
With all do respect, a person blind folded can do what you are trying to get accomplished.

Pete,

the pushrod seems to be moving the same as other but rocker dosnt seem to be pushing the valve down that is the issue. only reason i threw in thread count was because it shows that all are properly adjusted everywhere else. not sure what you are talking about blind person can accomplish. Lash is done I got that but there is an issue with what seems to be the #5 intake valve not opening up enough. Maybe i didnt explain myself well enough. I will post another video soon so you guys can see exactally what im talking about.

 

[coopin87]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Next steps on this 'project' would be to take a look at the lifter and cam . . . if the lifter is not cupped and the cam lobe looks OK, I'd be replacing the lifter. Oil type/weight is not a make or break on this one.

Ok so basically next step is pull intake manifold pull lifter out and inspect for cupping ect and shine light to see what the cam lobe looks like. If cam lobe looks ok and lifter looks ok replace lifter. (cant a lifter be cupped or wear down without the cam lobe going bad?)

 

[coopin87]

Re: 1996 mercruiser 5.7 with thunderbolt ignition ... Top End knock Please Help

Ayuh,... Just for the simple fact the rockers were screwed down Tight, 'n not really Adjusted at All,....


I'm goin' with the wiped out cam lobe.....

No oil in the world is gonna beat a 3/8s nut, torqued TIGHT...

Cant say im very happy about this but with my luck I believe you guys are prolly right. Im going to go ahead and start pricing cams anything else i should go ahead and replace since im going to be in there anyway. Biggest downside to this whole deal is i think im going to have to pull the whole thing unless i can figure out a way to pull my rear bench seat out. Need about 2 ft clearance in front in order to get cam out and new one in right now i have about 6-8 inches from front of water pump pully to bench back .

Half tempted to take it to the shop and let them do it. what would be an acceptable price to pay for this job?