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Donziweasel
05-16-2008, 05:42 PM
Today was sunny and in the 70's. Snowcapped mountains, blue torquise water, yack yack yack. Decided to run the 16 for the first time this spring. Started great, sounded fine, but I noticed a little vibration. Thought she was just shakin off 6 months of storage. Idled her to till she warmed up to 150 deg. and then put her on a mild plane and cruised at 30 mph for a half hour to break her back in after storage.

Then the problems began. Decided after 30 min of cruising to do a WOT run. When accelerating, it did not "feel" right. Tach got to around 4500 then it felt like it lost a couple of cylinders. RPM's dropped to 4100, speed 46 mph. Kinda surging, almost felt like a rev limiter cutting in and out. Backed out of it and it cruised fine. WOT, same symptoms, but only as it is starting to reach 4400-4500 rpm, and doesn't accelerate well. Felt boggy.

I stopped at an idle and lifted the hatch. There was a distinct knock under the starboard "passenger" side valve cover. Idled at 100o rpms back to dock, put it on the trailer, left it in the water and listened again. Knock still there. Oil pressure 20 psi at idle, 40 at cruise. Water temp never got over 160.

History- Finally, after 2 years of work and nightmares about it, had it running great, except for a minor oil leak. This fall, fogged the carb, disconnected all hoses, pulled plugs, pulled water pump, pulled freeze plugs, my usual winterization. I pulled the engine in November (for the 3rd or 4th time in two years) to fix the oil leak (timing chain cover). Replaced, started, ran fine.

I took it to Idaho Falls for some gel work on the bow and stern. While it was down there, the gimbal bearing housing on the exterior of the boat was cracked on one side. I was going to fix it myself, but due to too many projects, had a Merc dealer do it. While he was messing with it, I also had him check the valve lash. I set it right at the end of last summer with the installation of the new heads, intake, cam, carb, etc... but wanted to to them again after I had broke in these components.

That is about it. Boat came back in the same shape I had sent it away, freeze plugs out, hoses, water pump, etc...

I also fueled up this morning 20 gallons of high octane.

I do not want to spend this summer messing with it. I have sacrificed the last two summers working on this boat and have suffered many problems and setbacks. It is getting real old. Before I go tearing into it (literally), any suggestions to limit diagnosis will be much appreciate. I really am upset about having it run bad again. :hangum:

hardcrab
05-16-2008, 05:54 PM
Possibly a cracked distributor cap ?

justleft
05-16-2008, 06:00 PM
Hmmm,

"While he was messing with it, I also had him check the valve lash."

First thing is to pull the plugs and get a reading.

Reversion ? Messed up a lash setting and bent a push rod......

I feel for ya !!

Donziweasel
05-16-2008, 06:07 PM
First thought was crossed plug wires, but it wouldn't have run at cruising speed if that. Just too pissed to mess with it right now. Sunday is the earliest I can mess with it. Would still like suggestions on the simply stuff before I start tearing her down. Even getting the valve covers off and on is pain, mainly back on. Not counting out the distributer or a bent rod. Much easier to fix than a cracked head or blown piston. Thanks, keep em coming.

Just can't figure out how it would run so well to this. Also, noticed the throttle was a little stiffer than usual. One more thing, while the Merc dealer did the gimbal housing, my drive switch had taken a crap last year. Would go down with regular switch but had to raise it with the trailer switch. He fixed that as well. I know this probably has absolutly nothing to do with the symptoms, just want to get as much info out there as possible.

Dammit, I feel the call of the engine now, might poke my head in there. Ahhh, to hell with it.

Scary thing is I am commiting to Lake Powell for the DACA gathering. Need it running right.

mrfixxall
05-16-2008, 06:20 PM
you said you fogged the engine,,start with sparkplugs & go from their.. a dead cylinder thats not firing will make the engine knock.

you said you had the rockers adjusted? may be too tight..if you have compcam lifters in the engine threir a anti pump up lifter,your only soppose to give them a max of 1 turn which = .100 i have mine set at 1/4 .025 because if anything were ever to happen in the valve train or the lifter were to pump up the valve wont kiss the pistons..:)

Donziweasel
05-16-2008, 06:23 PM
I really hope it is something external. I hate pulling those damn covers and running the rack. I guess I should not have let someone else mess with my engine. I built it and probably know it better than anyone else, especailly where to set the valves. Lesson learned.

Question is, would a bent rod or lash set to hard cause these symptoms. I know it will make a knock.

mrfixxall
05-16-2008, 06:38 PM
do you still have the stock rockers? do yourself a favor and get rid of the self locking rocker arm nuts and get a set of poly locks..i adjusted my whole valve train with a dial indicator,each pushrod,rocker,lifter and poly lock are numbered per cylinder,also i installed another allen set screw into each poly lock so they wont move if i ever have to take the valve train apart everything is already set..

Donziweasel
05-16-2008, 06:39 PM
Yeah, there stock. I was thinking of going to roller's anyway after I had gotten it running right last year.

kd5cue
05-16-2008, 06:42 PM
rejust the valves

mrfixxall
05-16-2008, 06:44 PM
Yeah, there stock. I was thinking of going to roller's anyway after I had gotten it running right last year.

If you do stick with the compcams stainless steel roller rockers,,alunimum ones suck inless you have the 1500.00 for jessels and even those give us trouble..but to be expected with a 740 cid motor and 4 kits of nos:wink:

MOP
05-16-2008, 06:55 PM
I'll put 50 cents on a push rod went through one of the rockers!

Phil

Donziweasel
05-16-2008, 06:59 PM
Found a problem. Found a loose plug wire on the distributer. Was off the terminal, but the cap was still on. Man, would be real nice if this is it. It went to one of the cylinders on the side with the knock. It probably was arcing enough to fire the cylinder at low speeds, but not enough electricity at WOT to fire the plug. Felt exactly like that.

MOP- Might be a valve or rod. Still easier than a cracked head or blown piston. Maybe I was just being paranoid about the knock. Some boats just have little "ticks".

Problem was, no one on the lake. I didn't really want to mess with it, have a break down, and be stuck. Figured it was best to get it on the trailer and home.

One thing, knock was ony at idle at 650 rpm's. At 1000 it was gone, same with the rest of the rpm's.

Fixall, wish it was 700+ hp with 3 stage NOS!

mrfixxall
05-16-2008, 07:04 PM
Found a problem. Found a loose plug wire on the distributer. Was off the terminal, but the cap was still on. Man, would be real nice if this is it. It went to one of the cylinders on the side with the knock.

off completely? showing the terminal of the cap or just resting on the ternimal?

Donziweasel
05-16-2008, 07:14 PM
I was looking at the distributer and noticed one cap higher than the rest. Pushed down and it clicked into place. Not sure if it was touching the terminal or not, but it was definetly not seated on the terminal. Even if it was just close and not touching, it could have arced and fired the plug or maybe it wasn't firing at all and I couldn't tell at 30 mph. I haven't driven it in over 7 months.

RickSE
05-16-2008, 07:35 PM
I used to have a sticky lifter in my Olds that would only clack at lower RPM's. (1) can of marvel Mystery Oil in the oil would fix it for a little while but the clack would come back after the MO burned off. I eventually had to fix it for good.

As suggested I'd check the valve adjustment. I've had rocker arm lock nuts come loose and back off.

gold-n-rod
05-16-2008, 08:16 PM
A major miss will cause a knock. Once, I powerwashed the engine in a Caddy (the 4-6-8 model). I got the ignition wet and it missed and knocked like crazy. I limped it to a shop thinking I'd busted something. The next day, when they got to looking at it, it ran (and sounded) just fine. Whew!!!

Donziweasel
05-16-2008, 08:22 PM
Gold-n, do you think a cylinder missing at 600 rpm's could cause a little knock? 1000 rpm is not that much higher, but it dissappeared. Be real nice if a loose plug wire was the culprit.

Rick, I use to use some of that. Back in the early days, if an engine in a bus had a lifter making noise, would add some to try and get it through the season. Even a bus down for a day back then would kill me. Sometimes it worked, sometimes it didn't.

ky-donzi
05-16-2008, 08:43 PM
Donziweasel

I have seen a mis adj valve cause many problems.

One thing to consider is that at low rpm your engine is not very strong...HP wise. When at idle if there is much of a problem at all it shows up. For example fouled plug sometimes will fire when the engine is at mid range but miss at idle and high rpm. I have seen rocker arms that were to tight and cause a miss at low rpm. Put a vac gage on the intake and look for eratic reading. Also you can pull one plug wire at a time and see where the miss is.

I would look at the valves since that were messed with

gold-n-rod
05-16-2008, 08:46 PM
Gold-n, do you think a cylinder missing at 600 rpm's could cause a little knock? 1000 rpm is not that much higher, but it dissappeared. Be real nice if a loose plug wire was the culprit.

I think it could. I'm betting your next trip out will be trouble free. :)

MOP
05-16-2008, 08:49 PM
Usually don't get a knock from a wire being off, you sure can with cross firing which is what I believe gold-n-rod experienced. first run can be a challenge at times things just turn up! Did the knock match engine speed or was it erratic?

Donziweasel
05-16-2008, 08:55 PM
I only heard the knock at idle (600 rpm). Loss of power at WOT. Like a cylinder wasn't firing. Surged a little like it would fire occasionally. Either way, a plug wire not seated on the distributer is definetly a problem, if not the problem. I think that was it. Sunday I will find out as I found a Bronco body in Park City I am going to p/u tommorrow. Rented a car hauler and everything.

Next week I will probably run the rack again, just to make sure. I am NOT bashing boat mechanics, but for all I know, he migh tnot have even run the rack. Charged me for it though.

Jamesbon
05-16-2008, 09:03 PM
Do a quick compression test. The results should tell you allot about what's going on inside. Good luck! God's speed!

Donziweasel
05-16-2008, 09:06 PM
I know, it would tell me a lot. The reason I am skirting around it, even though I know I will probably do it, is getting to the plug holes. Almost impossible with my exhaust manifolds.

Donziweasel
05-16-2008, 10:01 PM
Poodle, gonna give me your opinion?:wink: You, Buiz and Rootsy know my setup pretty well.

Donziweasel
05-17-2008, 07:21 AM
Bout time you woke up:wink:. Will slap one on today when I get back from Park City. You weren't kiddin about the cell phone, tried to call last night.

You have to cut me some slack on the wire. Since had not messed with it, wouldn't think it would be off. I actually caught it at the same time Boo Boo said we could go to Powell DACA. Happiest minute of my life!

How did the Critter act when you chucked a wire?

It's 8:15 at AOTH. All the boats at the dock. What ever happened to coffee and a Donzi ride? Hell, even looks nice there today.

Donziweasel
05-17-2008, 07:33 AM
Starting a new movement-"People for the Ethical Draining of Cumberland" Or PEDC for short. :smash: