Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

[HenryBoat]

I have a 1988 Mercruiser 5.7L (350 CID) with 260 HP I/O. The spark plugs are very difficult to remove and install. Do the exhaust manifolds need to be removed for this engine? My normal deep well 5/8" spark plug socket wants to "bind-up" when removing or installing the spark plugs. I have also tried a "very thin wall" socket, but it does not help. I am afraid that I will break something because the plugs will not start into the holes without cross threading or breaking the ceramic when I try to tighten the plugs.

Does anyone know of some special tricks to change these spark plugs?

Thanks,
-Henry

 

[searay3]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

A lot depends on the boat and how the engine is placed. Some engines have to come out, seems crazy. I can gain access to mine by removing the alt on one side, and a cooling hose that goes to the manifold on the other. Just have to take a look and see if there is anything you can easily remove to gain access.

 

[bruceb58]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

Shove a rubber fuel hose over the plug and use it to start threading it. Make sure you use anti size lube on the threads. Then try your socket.

 

[DHPMARINE]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

I have yet to pull a motor to change the plugs,but I see that day down the road.If only we could find away to educate the public on the aspect of service,and how the cost greatly arises,depending on access to the motor. (before they bought the boat).It is just difficult to explain to a customer why we have to pull the motor to replace the starter,or to install a remote oil filter (that the boat buider should have done in the first place).I have asked a few customers to 'try' to touch the oil filter,never mind change it.That works pretty well.

Even the boats we sell are difficult to drain the blocks if they have rear entry.

Two of three ideas.A plug socket with the 'swivel'built in seems easiest to me.There are multi-jointed plug starters out there these days.I even have a length of tubing I use as a remover/starter for plugs.

DHP

 

[tommays]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

I have one with a T handle and flex built in that can get in pretty much anyplace ,the socket is tapered for clearance also

Its pretty low cost at most of the chain auto stores


Tommays

 

[Bt Doctur]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

Take the hex socket and grind off the hex to provide a taper.

 

[John_S]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement

I'll 2nd the T handle spark plug wrench. Works for my 5.7L, which had the same binding against the exhaust manifold. It was less than $10 at Autozone.

 

[Don S]

Re: Mercruiser 5.7L (350 CID), 260 HP spark plug replacement