what are the symptons of manifold failure?

[inchman]

hi i have a 1988 bayliner trophy with a mercruiser 140 hp 3.0l engine. in my search to resolve a misfire ive descovered that my plug on cylinder 4 tastes salty. could this be a result of manifold breakdown. what are other symptons of a faulty manifold?

cheers Gary

 

[Uraijit]

Re: what are the symptons of manifold failure?

Tastes salty?

 

[Bt Doctur]

Re: what are the symptons of manifold failure?

bad riser/elbow would be my first choice, simple to remove and look inside.
next would be the manifold.

 

[Dakota47]

Re: what are the symptons of manifold failure?

look for water in engine oil..

 

[inchman]

Re: what are the symptons of manifold failure?

there is no oil in the sump or the rocker cover. would a bad manifold cause a misfire?

 

[TilliamWe]

Re: what are the symptons of manifold failure?

Yes. If enough water was leaking into the exhaust valve it could run into the piston and not combust.

 

[inchman]

Re: what are the symptons of manifold failure?

sorry there is no water in the oil in the sump and and the oil in the rocker cover, my misfire is about 3200 rpm

 

[getinmerry]

Re: what are the symptons of manifold failure?

my plug on cylinder 4 tastes salty.

Every good mechanic sucks on old sparkplugs while working...and uses old dristributor caps for his Lucky Charms in the morning.

 

[Dakota47]

Re: what are the symptons of manifold failure?

sorry there is no water in the oil in the sump and and the oil in the rocker cover, my misfire is about 3200 rpm

Thats good. check the rotor & dist cap.

 

[inchman]

Re: what are the symptons of manifold failure?

there is 0.008 play in the distributor shaft, not good i know maybe a change to electric like pertronix would help. the salty plug is still a worry

 

[bruceb58]

Re: what are the symptons of manifold failure?

The play in your distributor shaft will effect your dwell if you have points. The pertronix would help that situation.

I need to know...what prompted you to taste your plugs? Is that some sort of Irish tradition?

 

[Coors]

Re: what are the symptons of manifold failure?

I've smelled plugs, but never thought about a taste test. And wouldn't know what each taste meant.

 

[subcrx]

Re: what are the symptons of manifold failure?

check for steam. remove your oil filler cap. Couldnt figure it for the longest time till it was too late.

 

[Ed R]

Re: what are the symptons of manifold failure?

First of all, number 4 cylinder is closest to exhaust elbow, there is a check valve, which we call a flapper valve that keeps water out of exhaust system. Usually, when this valve fails, number 4 cylinder is the first to encounter water intrusion.

ER

 

[subcrx]

Re: what are the symptons of manifold failure?

I wouldn't rely on the flappers for much.

 

[fishmen111]

Re: what are the symptons of manifold failure?

With no signs of water, I truly doubt that it is the elbow/manifold. Every time I have lost one, it would still run beautifully even with extra quarts of water in the oil. For a specific rpm miss, I would question the plug wires, coil, dist. cap and/or distributor itself. Have you tasted any of those? Have you given it a complete tune up? If not, I would along with a compression test (first).

 

[inchman]

Re: what are the symptons of manifold failure?

ill give you abit of back round. lol at the end of the season last year i noticed the boat going on 3 cylinders. I changed the plug leads, points, condensor and cap in the hope that it was something easy fixed. still 3 cylinder ( and running sweet) did a compression test no3 had 20 or 30 psi compared to 130 on the rest. I pulled of the head and the exhaust valve on no 3 was fried, got 2 new valve for no 3 and had the rest of the valve and seats reground, i put everything back together with new head and manifold gaskets and it wass running sweet. put the boat in the water and it started to miss. cleaned the carb, still missing. I noticed water air bullling up fron the port between cly 2 and 3 and this prompted me to taste the plugs ( they looked great maybe a bit white) and thats where i am now.

cheers Gary

 

[gooders]

Re: what are the symptons of manifold failure?

Only last weekend I had a misfire on my 3.0L, turned out to be a loose wire on the coil.
Just a thought but sometimes the problem is so obvious its missed.:redface:

 

[Dakota47]

Re: what are the symptons of manifold failure?

Replace the guzenhowtion.

 

[Boatist]

Re: what are the symptons of manifold failure?

I would do another compression check first.

Signs of bad manifold or leak at the riser gasket is, Number four plug looks cleaner than the rest. also in salt water the may see sign of rust. Engine will miss and pulling off the spark plug wires one at a time you will usually find number 4 missing. Number 4 is usually the worst because when the water get into the exhaust chamber it runs down hill to the lowest cylinder and that is usually number 4.
Also when first start getting water into the exhaust the miss will only be at low RPMS.
Running on Muff can see steam coming out the exhaust.
If it gets bad enough then will start seeing water in the oil.

Also if one cylinder fills with water you will not be able to turn the engine over with out pulling the plugs.

When you had the head off did you check for a cracked Block. Also did you drain the block before the winter.