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Update on my 350

H

hippie

Regular Contributor
"We tore the engine down this

"We tore the engine down this morning and found the upper half to be new! The heads were in excellent condition as were the valves. The head gaskets were not blown nor wore. The rockers were all in excellent condition and adjusted well. It was obvious to all that some one had been inside this engine before us. It has thick rubber valve cover gaskets which are not standard. The cylinders are all smooth and no carbon anywhere. The pistons are in excellent shape but they are stamped with numbers. Not just 1 then 2 but they all have a bunch of numbers on them? Its good news that nothing needs machined but why doesn't it rev up? BTW, when pulling off the heads some water got into the cylinders and it was there all day and did not go down at all. This shows me that the cylinder walls and piston rings are good and tight. We are replacing the solenoid/starter, fuel pump, oil pump and pan gasket. We are going to check the cam clearances and the timing chain so we'll replace the timing cover gasket. The carb was just rebuilt as was the dist. and a new module. In essence I'll have a remanufactured engine plus all new parts that normally don't come with a remanufactured engine, but it is a mystery why it will not rev up. Any suggestions please post them. Thank you all, Bob"
 
"Did it work properly with the

"Did it work properly with the old engine?
The thick gaskets are standard, now neoprene.
Unless you have a 1.32-1 gear ratio in the upper the motor should atleast go 4800"
 
"Bt Doctur, This is the engine

"Bt Doctur, This is the engine that has been in since I bought it 7 yrs ago. It would rev high but now with a 14X15 prop all I get is 3500. Before I would get 4800 with a 15.5X21 prop. That is why I am tearing it apart. Also I forgot to mention we found a head gasket to have a water hole plugged at the gasket. I had an over heating problem but I doubt that 1 hole would cause it to over heat to about 240*. Thanks again, Bob"
 
Exhaust restriction???? A vacu

Exhaust restriction???? A vacuum gauge can be used to check for vacuum at WOT and to spot any restriction in the exhaust system.
 
You say the distributor was re

You say the distributor was rebilt but did you check to make sure it was advancing properly? It sounds like the engine isn't getting enough advance. You may have a problem with the advance mechanism It should be getting in the neighborhood of 32 to 38 degrees.
 
"All hoses (water) and

"All hoses (water) and risers and exhaust manifold are clean. No problems there. Thank you, Bob"
 
"No, we did not do a compressi

"No, we did not do a compression check. The gasket imprints showed tight seals without any folds or tears. All bolts felt evenly torqued when taking them out. The plugs were all the same color and none were "oily". One thing I did discover, all plugs were MR43T (AC) but two plugs were actually shorter in length than the other 6. The two plugs were about 3/8" shorter where the electrode would be inside the cylinder. That piston did have a little dark tan residue on the top. I don't know what else. We are going to put it together this week after first wire brushing the valves and cleaning everything. Since we have the engine out of the boat we will change the starter/solenoid, oil pump and fuel pump. If anyone has any ideas please post them because we do need help figuring this one out. Thank you all, Bob"
 
Install remote oil filter kit

Install remote oil filter kit and remote oil drain kit. Makes self servicing much easier.
 
"If you had 2 plugs that were

"If you had 2 plugs that were not in the cyclinder as far as the others I would say you had a problem.

I suspect it would not fire correctly at some rpm range. it may work but not all the time as well as the others. I find this hard to understand if they are all the same part number.

Buy new plugs and you can use r43T from a auto store and save some $$$

Gap is .035

Lightly Oil the head bolt threads before installing,"
 
"I bought all 8 plugs at an Au

"I bought all 8 plugs at an Auto Zone (I mean auto store). All were packaged in the same wrapers and all were marked the same, MR43T. All were bought at the same time. I gaped them all at .035 and while installing them I never noticed a difference. Who would have thought of it? Thanks again, Bob
PS- Guy, how do these remote drain and oil filters work? Thanks, Bob"
 
"remote drains as I beleive Gu

"remote drains as I beleive Guy is refering is a hose that has an adapter that screws into the oil pan drain, then the other end of the hose is pulled through the transom garboard plug, then the plug on the end that is removed to drain the oil..

the remote oil filter is a kit that has an adapter that screws into where the oil filter goes, and a couple hoses and another peice that can be placed in a more accessible place where the filter screws into that."
 
Brian said it right. To me th

Brian said it right. To me they are well worth the money spent. The filter on my 4.3L is mounted on the front of the port exhaust manifold.
 
"[b]Quote: Any suggestions p

"Quote: Any suggestions please post them. Thank you all, Bob

Bob, I do Volvo Penta, and just stuck my head in over here on the MC side.
Just a thought if all else was eliminated:

The odd spark plugs certainly did not help any.
Not taking a compression test does not help any either.
Having an ignition curve to show us would have been helpful.
But you're past that now.

I know that you mentioned that you checked to see what your ignition was doing throughout the RPM range!
Did you do so with a digitally advancing timing light?
Did you map this out?
The reason that I ask is... is can be common to misinterpret the use of this type of timing light... or misuse the mode.
Many, even good mechanics, do not concern themselves past BASE timing on these engines. That is what got me to thinking about this.
They assume that the module is taking care of this! A new module may not mean anything if not working correctly.
IMO, it is far more accurate to use a standard ole strobe light on these and see in Real Time/Real Degrees, just what the ignition is doing outside of BASE mode.
TAT is just too dang critical on a marine gasser.
GJack also mentioned this... he and I were thinking along the same lines, although we part ways with a TA of 38 degrees.
You do not want 38*. That is far too much TA.

It's a shame that you have torn this down only to find nothing abnormal.
I hope you find the problem."
 
"Brian, Guy and Ricardo- Thank

"Brian, Guy and Ricardo- Thank you for the ideas. A remote set sounds good. Ricardo, I originally set it with an old fashion light. The timming degree plate ?, is old and I couldn't see the numbers. Then a mechanic showed up with a new "does all" type light and said I was at 10*BTDC and it calls for 8BTDC. Not a biggie. He also checked the timing curve as I took the rpms up and said we were at 31 or 33*, I can't really remember. As I think about it the plugs were put in this summer long after this problem started. I just think of what would cause a drop in power like this!!Well, if you men think of anything else I can try please speak up. Thanking all of you, Bob"
 
"We decided to replace the oil

"We decided to replace the oil pump, fuel pump, solenoid/starter while we have the engine out of the boat. My partner noticed a very small amount of discolorization on the engine block at the bottom of a head gasket while cleaning them up. We are thinking the entire head on that side was loose and the water leaked down to the bottom of the gasket and gave it a light brown rust color. This would account for a lack of power (low compression on these 4 cylinders). We looked at the crank and everything there is exceptionally clean also but when we drained the oil it was very black and I didn't hardly run the boat this year. I'm thinking since the head was not on tight if exhaust could have caused the black appearance of the oil?

One question though, did they put plastic blue colored water drain plugs (the kind you can turn with your fingers) in a 1987 vintage block? I did not think so, so apparently somebody overhauled this engine prior to me. Thanks men, Bob"
 
"Well we put the engine togeth

"Well we put the engine together. We chased all bolts and threaded holes with a die. Used new head bolts, gaskets, etc. Everything got "anti-seize" compound. Cleaned everything to where it was spotless with "Berrymans" cleaner. Put 5 coats of paint on entire engine. The only new thing we did that was unknown to me- we primed the hydraulic lifters before adjusting the valves. It makes sense to do so. We also put it in the boat and had a difficult time aligning the 4 motor mounts. Anyway, we'll see how it works this Sat. Thanks again men, Bob"
 
"Bob, if there is a "Next

"Bob, if there is a "Next Time"...... (or when there is a next time)......., try leaving the cam followers (lifters) un-primed until after you get them set using the 8 stop "static" method!
You go right down the firing order setting each pair for each cylinder @ TDC C/S as you go.

This method is much accurate as you can watch as each plunger moves within the body to the tune of it's .080" to .100" travel!
You'll often find that you will not need to go back through them dynamically.

Once set, then prime your oil system as you rotate the crankshaft assembly a minimum of 8 or more cycles.

Sounds like you are getting close to a test run!

."
 
"I do need a little help. Does

"I do need a little help. Does anyone know of a diagram that shows where all the raw water hoses go? I forget where some go. Mercruiser schmatics shows a portion but I need to see in relation to the engine itself. Many thanks, Bob"
 
"Bob, It would help to have mo

"Bob, It would help to have more info: Year/model/closed cooling system or raw water cooling, old school log mans or centerise mans, etc????"
 
"Ricardo, It's a 1987 merc

"Ricardo, It's a 1987 mercruiser 350 CID rated at 260 hp. The main thing is on the thermostat housing. Mine is raw water setup with 6 hoses off the thermo housing. Do the 2 hoses coming from the outlets which have the balls go to the risers? and then the 2 hoses from what looks like steer horns go to the 90* fitting at the bottom of the exhaust manifolds OR are they vice versa? Thank you, Bob"
 
"Bob, is this what you need?<[

"Bob, is this what you need?
296270.jpg
cooling
 
"Bob,

The two upper hoses &

"Bob,

The two upper hoses (1 inch or so diameter) go to the elbow/risers. The poppet balls are there to restrict water flow based on pressure. The newer type thermostat housings have a "fixed" orrifice.

The two lower(1 inch or so diameter)go to the bottom of the manifolds. These supply full water after the thermostast opens. some is bypassed thru a small bypass hole in the housing.

If hooked up in reverse the outcomming water would be very steamy, seen that several times. before."
 
"Don, that is exactly what I n

"Don, that is exactly what I need! Thank you. Kghost, I understand your explanation completely and it makes sense. Again, Thank both of you, Bob"
 
"I do need a little advice. We

"I do need a little advice. We have the engine together and installed in my boat. However, when I turn the key on to crank the engine I get a noise from the starter solenoid and the engine does not crank. The 50 amp. circuit breaker doesn't seem to be working. (you cannot push the red buttom in). My assumption is the circuit is stuck open causing the engine not to crank. Is this a plausible solution that the circuit breaker is bad? Thank you, Bob"
 
"Bob, What is your "at res

"Bob, What is your "at rest" battery voltage? (not immediately after a charge)
Also, check your ground cable as well as any positive battery cables (connections for corrosion and tightness).

The red button circuit breaker is working (continuity) if you have power at the helm. From what you describe (the clicking) you do have power there!

If not a cable issue, then you may have a starter motor issue or low voltage..... or ALL."
 
"Bob,

I'm responding a

"Bob,

I'm responding a little late, but I too had the different length spark plugs issue....here is what I posted back in late May, after I contacted AC Delco...

Jeff

Posted on Thursday, May 28, 2009 - 11:46 am:

--------------------------------------------------------------------------------
Thought I would share what I heard back from ACDelco on the different sizes of MR43T plugs..

"We appreciate your email with regards to ACDelco spark plugs part number MR43T. Part numbers 5613438 (ACDelco) and 19157985 (GM) both reference back to MR43T.
The MR43T plugs underwent a design change. They are now longer, which should not be a problem as long as they are not actually making contact with anything. The plugs were redesigned to provide consistent resistor performance and "fantastic" flashover protection"
 
"The batteries are brand new,

"The batteries are brand new, never even started the motor with them. They show 12.5. No, the outdrive is not off due to the boat being in water. I am pulling it next week but will need directions on aligning the coupler. Yes, the motor turns by hand, we did a complete rebuild on it. The starter motor was never used, it and the solenoid are brand new. As for the red button circuit breaker and the neutral switch beside it, both are gone. They are just something else to go wrong when out on the water. It is now wired direct. But what concerns me is this coupler alignment. Never heard of doing this. We pulled the engine and put it back in without doing anything to the outdrive. We slide the engine with the spline attached back into the outdrive and bolted the motor mounts down. The 3/4" bolts in the rear lined up good as did the front mounts but the lags on one side were striped so we epoxied them in. Please expound more on "lining up the coupler". Thank you, Bob"
 
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