3.0 mercruiser valve adjustment

[Whitemustangman]

yeah your other boat is ok. I had a 3.0 for 20 years after 800 hrs pulling tubes and skiers still had 140-145 psi, which given how many hours it was above 4 k rpm is pretty amazing.

if you replaced the rockers, balls and nuts maybe you have a parts mismatch ? Maybe try a set of poly locks?

The rockers and hardware are original, they’re in good shape, I can’t for the life of me figure it out lol

 

[Scott Danforth]

The rockers and hardware are original, they’re in good shape, I can’t for the life of me figure it out lol

did you bore and hone? or just dingleberry the bores?

did you verify TDC on cam/timing gears

 

[Whitemustangman]

It was bored .030 over and honed to the pistons by the machine shop, I verified proper ring gap and piston clearance prior to final assembly. The cam and crank are timed correctly. It has great compression but only if I remove preload from the lifters.

 

[Whitemustangman]

did you bore and hone? or just dingleberry the bores?

did you verify TDC on cam/timing gears

I was thinking maybe the valve springs are weak? I duno what else it could be. I figured the machine shop would have checked the springs… maybe not

 

[brian3127]

It was bored .030 over and honed to the pistons by the machine shop, I verified proper ring gap and piston clearance prior to final assembly. The cam and crank are timed correctly. It has great compression but only if I remove preload from the lifters.

are the lifters hydraulic they need to be pumped back up with oil. possibly

 

[Whitemustangman]

are the lifters hydraulic they need to be pumped back up with oil. possibly

They are hydraulic lifters but the problem seems to be that they’re not adjusting themselves, they’re acting like solid lifters from what I can tell. I’m gonna pull the lifter cover and see if they’re collapsing when I preload them or not . I’ve built a ton of car/truck motors and have never had a problem like this

 

[alldodge]

Was the block boiled?
If not maybe the oil passages are clogged?

Could verify by starting the motor and see if oil works up the push rods

 

[rustybronco]

Are the lifters correct OEM for the application? To me it seems like the lifters won't bleed down correctly. I've seen so called anti-pump up lifters in the past which wouldn't bleed down. Those obviously were not factory lifters. We got past the issue by bringing the push rods to zero clearance and tightening the nut(s) slightly past that point. They were replaced shortly thereafter.

There is a tester to check the lifter bleed down. Maybe you can duplicate the tester or find someone who has one such as an engine rebuilder.

From the FSM...
"
Following procedure should be completed only if readjustment is required.
1. Run engine until it reaches normal operating temperature, then remove valve cover.
2. With engine running at idle, loosen valve rocker arm nut until valve rocker arm starts to
clatter.
3. Turn rocker arm nut down slowly until clatter just stops. This is zero lash position.
4. Tighten nut 1/4 additional turn and pause 10 seconds until engine runs smoothly. Repeat
additional 1/4 turns, pausing 10 seconds each time, until nut has been tightened 3/4 turn
from zero lash position."

This might give you some insight into whether or not there are any issues with the lifters. That is if you can put up with the oil splashing.

 

[rustybronco]

One more thing. They used to make a clip for SBC's that you put over the push rod oil hole in the rocker arm that had some sort of fabric to keep the oil from squirting all over the engine while it's running.

Rocker arm deflector clips. Similar to these... www(dot)summitracing (dot)com/parts/WMR-W80565

 

[salvageyard saviour]

Just had a similar issue with a SBC 350.
Filled the lifters with oil during reassembling per manual and they also acted like solid lifters, only able to get compression with no pre load.

Soaked the oil empty assembled lifters in oil overnight and then cycled the plunger while submerged to prime.

All good, proper pre load and compression now

 

[Whitemustangman]

Was the block boiled?
If not maybe the oil passages are clogged?

Could verify by starting the motor and see if oil works up the push rods

Yes, it was cleaned thoroughly before and after machine work, I ran brushes through every passage and oil flows good from every push rod.

 

[Whitemustangman]

Are the lifters correct OEM for the application? To me it seems like the lifters won't bleed down correctly. I've seen so called anti-pump up lifters in the past which wouldn't bleed down. Those obviously were not factory lifters. We got past the issue by bringing the push rods to zero clearance and tightening the nut(s) slightly past that point. They were replaced shortly thereafter.

There is a tester to check the lifter bleed down. Maybe you can duplicate the tester or find someone who has one such as an engine rebuilder.

From the FSM...
"
Following procedure should be completed only if readjustment is required.
1. Run engine until it reaches normal operating temperature, then remove valve cover.
2. With engine running at idle, loosen valve rocker arm nut until valve rocker arm starts to
clatter.
3. Turn rocker arm nut down slowly until clatter just stops. This is zero lash position.
4. Tighten nut 1/4 additional turn and pause 10 seconds until engine runs smoothly. Repeat
additional 1/4 turns, pausing 10 seconds each time, until nut has been tightened 3/4 turn
from zero lash position."

This might give you some insight into whether or not there are any issues with the lifters. That is if you can put up with the oil splashing.

I tried adjusting the valves like that, it would run rough when I did the 1/4 turn then smooth out, but afterwards I would check compression and it was low….. I don’t know but it really has me pulling my hair out , I’m gonna do a leak down test when I get a chance and see what that shows

 

[Whitemustangman]

I tried adjusting the valves like that, it would run rough when I did the 1/4 turn then smooth out, but afterwards I would check compression and it was low….. I don’t know but it really has me pulling my hair out , I’m gonna do a leak down test when I get a chance and see what that shows

I bought a cam/lifter kit for the engine so I hope they’re correct lol

 

[Whitemustangman]

I bought a cam/lifter kit for the engine so I hope they’re correct lol

 

[Whitemustangman]

Just had a similar issue with a SBC 350.
Filled the lifters with oil during reassembling per manual and they also acted like solid lifters, only able to get compression with no pre load.

Soaked the oil empty assembled lifters in oil overnight and then cycled the plunger while submerged to prime.

All good, proper pre load and compression now

I soaked them for about a week before I got around to assembling the engine. I’m gonna take the lifter cover off and see if they’re acting solid or adjusting

 

[rustybronco]

I tried adjusting the valves like that, it would run rough when I did the 1/4 turn then smooth out, but afterwards I would check compression and it was low….. I don’t know but it really has me pulling my hair out , I’m gonna do a leak down test when I get a chance and see what that shows

You can make a leak down tester if you have a way to regulate the air source. It is easily made from a compression tester and you ONLY need one gauge! Just put a shutoff valve past the fixed orifice and the gauge, then the gauge can be used to read regulated pressure (100 psi) when closed and cylinder leak down psi when open. I can post a picture of mine if you would like.


"I tried adjusting the valves like that, it would run rough when I did the 1/4 turn then smooth out (which it should do.), but afterwards I would check compression and it was low…." Throttle plates are open correct?

 

[Whitemustangman]

You can make a leak down tester if you have a way to regulate the air source. It is easily made from a compression tester and you ONLY need one gauge! Just put a shutoff valve past the fixed orifice and the gauge, then the gauge can be used to read regulated pressure (100 psi) when closed and cylinder leak down psi when open. I can post a picture of mine if you would like.


"I tried adjusting the valves like that, it would run rough when I did the 1/4 turn then smooth out (which it should do.), but afterwards I would check compression and it was low…." Throttle plates are open correct?

I have a leak down tester, no need to make one. Yes throttle wide open and all plugs out