Engine running horribly - considering scuttling the boat!

[loco]

Hi all,
I've been having a real nightmare with the boat recently, it's now running horribly lumpy, and making some horrible sounds:
https://www.youtube.com/watch?v=P3n8IazfGr4

A quick overview of how we got to this position:

- Engine's a 4.3L V6. Coming up to four years old.
- Power steering pulley failed last august. I *think* it was the PS pump, but essentially the boat's not been out for an extended run since then. It has been run a fair amount in the harbor, and I've replaced the PS pump and pulley.
- The carb got a rebuild over winter as the accelerator pump assembly was nasty. After testing manifold vacuum, I saw that it was erratic and low, and found a leak on the inlet manifold.
- I contacted the engine manufacturer for a manual. I went to the torque chart, and found the inlet manifold torque at 48Nm. Trying to tighten up this tight didn't feel right, but it fixed the leak, and manifold vacuum went up and became static.
- Going back to the manual, I notice in the exploded diagrams that they've given me a manual for the pre-vortec engine, where the bolts go diagonally into the heads, rather than straight down. Torque setting for the vortec engine is only 15Nm. Brilliant.
- I check the oil. Level is high and the oil is milky. I'd clearly busted the inlet manifold gasket by over-torquing it. And it's raw water cooled, so that's salt water in the engine. Not a good day.
- I pumped the oil out, put some fresh oil in and a new filter. I changed the inlet manifold gaskets, carb gaskets, and RTV sealant. I torqued the damned thing up properly.
- I then ran it to get up to temperature (after giving RTV 24hours to set), and it sounds like it does in the video. I've pumped out that second lot of oil, and put more fresh oil and new filter in.

So, it's running like crap now, and tomorrow morning It's due to be taken out the water for what should have been the antifouling/leg work, so I really needed the boat to be running well today. It seems to be much worse at idle, and at points actually sounded OK at higher RPMs.

Possibilities I've considered:

a) Timing. I marked the position of the dizzy and the rotor as we took it out, and put it back as it was. I don't have the specific tool that needs to plug into the distributor before you can time it, though, so I can't test that right now. The noises it's making really don't sound like it's just out by a couple degrees though.

b) It's time to check/replace exhaust risers, and I'm seeing signs of water leaks. But I could be too late already and water has already screwed up the engine, and those noises are big end bearing failures or something. I ran a compression test, and all cylinders are between 165 and 170PSI, though.

c) The carb's not set right still, but it was OK when I took it off.

d) over-torquing the inlet manifold has caused some other problem. Balancer shaft bearings/heads/pushrods/crank....

e) The short time the oil was salty was enough to wreck the internals.


Any thoughts, people? Essentially, from having a corroded accelerator pump on the carb could have resulted in totaling the engine though a comedy of errors. I'm utterly exasperated with this thing. Thanks in advance.

 

[Scott Danforth]

Nothing to be angry about.

Vortec motors have 8 bolts in the intake, non-vortec have 12 bolts

Never ever came across a need to replace a power steering pump in a boat due to normal wear, they simply dont get enough run in a boat to wear out

I have replaced pumps due to lack of maintenance and neglect or over-tightening of belts

Specific tool for setting timing is a glorified paper clip. No excuse. Detailed in the adults only diy links

Overtorqing the manifold can lead to failed gaskets. Not checking oil daily could lead to long periods with motor in oil. Thats a lack of maintenance issue

Regarding your motor. You obviosly boat in brine. When was the last time you inspected the manitolds and risers? Inspection should be ever 2 years or sooner

Worst case, you yank the motor, throw new bearings in it

 

[Lou C]

did you remove the plugs, ground the ignition and blow out the water?
use fogging oil to prevent corrosion?
Take off the manifolds & risers and see if there were actually water leaks (rust stains) in the exhaust ports?
Water in the cyls, can be from a blown head gasket, cracked head or block, failed intake gasket, cracked intake (there is a water passage to the front of the cyl heads, or a bad manifold/riser gasket, or rusted through manifold or riser.
Are you sure that that noise is not a bad front water pump, they can make noise but usually its a grinding when the bearing goes bad.

I had a blown head gasket, salt water in a cyl, but was able to save the block by blowing the water out, draining the engine and coating the cyls with oil by spraying fogging oil in the cyls repeatedly. I took it apart this winter and there was no rust in the cyls at all. I had 2 blown headgaskets, and both heads had cracks in the center cyls exhaust ports. Got a set of re-man heads and am going to put it back together this summer.

exhaust manifolds & risers in salt water need replacement between 5-7 years if you want to be on the safe side. If you push it beyond that, your chance of water in a cyl really starts to go up.

It sounds like its time to at least take off the heads, and see what they look like, and what the block, cyls and pistons look like. If you wind up replacing the engine consider adding closed cooling,.

 

[Lou C]

No Title

I think you'll be doing this soon....

 

[alldodge]

Hate to hear the bad news, but if the water is coming in from the intake, then at least its an easier fix. If its coming in from the block or head, it needs to come out

 

[loco]

Thanks for the responses, all.

I've already fixed the intake, so I just have to see how that goes. If water is still coming into the block, then I'll shed a tear and start pulling the heads off.

I'm mostly concerned as to why it's running so rough now. I saw in the manual that the delco tool is just a connection bridge and +12V source, but the pins are so tiny, it'll need the proper connector instead of stuffing wires in there somehow with the engine running. The official ones cost $47 to get them shipped where I am! My local engineer does the work on my drive leg, and as part of it, I get to antifoul my boat in his yard, so he's coming down tomorrow, and I've asked him to bring the timing gun.

Though, does that engine really sound like it's just the timing out in the video?

Scott: it could have been the pulley that was too tight on the PS pump. I read risers were replaced every 4-5 years, with the bolts being torqued once a year, hence me doing them on the engine's 4th birthday, but I guess that could be too far apart, as you suggest. I hope I've got them in time - will know tomorrow.

 

[alldodge]

I've never found a motor I couldn't turn the distributor and listen to get it running smooth and idle, so long as there is nothing else wrong with it. Your motor sounds bad to me, lot of metal sounds when it slows down.

 

[Lou C]

Salt water in oil = stuck valves = rough running. Mine had close to normal comp test results but when I took it apart 2 valves were stuck open. No bad noises while running though.

 

[loco]

Hi all,
Just an update - it turns out that it was indeed the timing. It was way too advanced. A good session with a timing gun, and the engine is singing again.

Massive, massive relief.

Thanks again for everyone's help.