1988 340 Express

Snapon24

Active Member
Sep 16, 2018
114
Long Island, NY
Boat Info
1988 340 Express Cruiser
Engines
Twin FWC 7.4L Mercruisers w/Borg Warner straight drives
Hi Im looking at a 1988 340 Express with 454 Mercruisers with 1300 hours on them. I am a little concerned with the hours. What is average life expectancy of these engines provided they were properly maintained? Ive read well over 2000 and ive also read that they will need valve jobs right around now. Would a compression check be good enough to check current condition? I have to find out when manifolds and risers were done last. Havent seen it in person yet but rest of boat looks very clean and neat in the pics. Guy is asking $9k Thoughts?
 
Everything looks better in pictures than in person. As for the engines 1300 hours on well maintained engines is no concern. Yes the top engine may need to be redone if it already hasn't but if it reaches top rated rpm and the compression is within tolerance it could run another 1000-1500 hors before repower is needed. There is an older Wellcraft Gran Sport at our yacht club with al most 4000 hours and still runs well. The heads have never been off either.
 
it's all about maintenance. if the previous owner performed regular oil changes, proper winterization, etc., there's no reason why you won't get a long life out of those power plants. i can tell you, though, that with a boat that old, you may have issues with rubber--wherever you find it . . . gaskets, hoses, belts, spark plug wires, as well as window seals, water system, etc. so, may be a good idea to change all of that out, where feasible, to stay on top of it. some of your electrical connections will have oxidized and corroded, too. one other point to consider--condition of the gas tanks. that's thirty years of opportunity to build up sludge, ethanol issues, etc., and those are a pain in the butt to resolve.
 
Ive noticed there is a 340 Express Cruiser and 340 Sundancer in 1988. They look very similar to me in pics. The only differences I know of is the dancer has v-drives while the express is straight drives, different cabin layout, and cabin door is in the center on the express while on the port side on the dancer. What other differences are there?
 
If you haven't planned to already, be sure and get a survey on the hull and engines before you purchase. $9000 seems a very low price for that boat....there must be a reason and you need to find out all you can.

I loved my '89 340 Sundancer. It was my first "Big" boat and first with twins. It had plenty of room, was easy to handle and I had 4 good years with it. I preferred the Sundancer to the Express because the aft cabin layout worked better for us.

Good luck and don't forget to get the survey.
Shawn
 
Hi so I just bought the boat, ended up getting it for $8K. Needs a canvas and few odds and ends but very clean overall and well taken care of. Does anyone know how the factory sea cocks come off? Theres 4 small screws holding them it looks like but that cant be it. Do they screw on to something? I want to replace them since 3 out of 4 are frozen. Does the canvas have to be custom made or is there somewhere I can get one that's premade for a 340 since its a common boat? Also is there a replacement ice maker that will fit in the same space? Thanks
 
congratulations. seacocks should screw into the flange from the other side of the boat, if i'm getting your drift. as for canvas, pretty much impossible to find templates from the 80s. i have a great guy in greenwich, if you can get your boat onto this side of the sound. otherwise, you'll have to find someone local. expect to pay from $3500 to $7000, unless you opt for a camper set-up, which can be substantially more.
 
Are the sea cocks regular appollo style ball valves or are they the grocco type that were very popular on searay's of that era ---- valve with a lever on one side, and a small "tee" bolt on the opposite side? If the latter- you need to loosen the tee nut first.
 
Are the sea cocks regular appollo style ball valves or are they the grocco type that were very popular on searay's of that era ---- valve with a lever on one side, and a small "tee" bolt on the opposite side? If the latter- you need to loosen the tee nut first.

This plus they should be taken apart and lubricated with white lithium grease every year or two so they will work easily when needed. Don't use petroleum based grease as it with degrade the rubber insert.
 
Thank you. They are the Groco SV style. I just tried loosening the t bolt first and they are still stuck. I'll take them apart and clean and lube them. I guess as long as the rubber is still good then I can reuse them.
 
I took apart all the sea cocks.The ones for the engines came apart nicely and should clean up but the 2 smaller ones for the A/C and generator are destroyed, the handle ripped off the rubber insert. Can anybody recommend the best ball valve type to replace these old Groco SV valves? And how involved is it to change them out, just unscrew the old ones and screw on new ones? Has anyone done this before? Thanks
 
Ebay has many Groco seacocks of various configurations and sizes. I believe your 340 may have the triangle base seacock design. You should be able to find a suitable Groco "MARINE" seacock on ebay for under $100. BTW do not install a scoop style intake on the generator.
 
OK Thanks. I wasn't planning on replacing thru hulls right now since they look fine. The generator does not have a scoop but why? Wouldn't you need it to run it while underway? I decided to replace all 4 of the old Groco SV seacocks with new ball valves. I removed and cleaned up the engine ones and they work very nice if anyone needs them for parts or wants to use them as replacements. Message me for pics. They are the old Groco SV 1250 1-1/4" seacocks.
 
Re: scoop strainer for generator. When running on plane with the generator off a scoop strainer will "force" water into the cooling water side of the system and it will find it's way into the exhaust manifold and from there into the engine thru the exhaust valves filling the generator engine with water. When running the generator's seawater pump will have plenty of "suction"to draw in water from a standard mushroom thru hull.
 

Forum statistics

Threads
112,950
Messages
1,422,862
Members
60,932
Latest member
juliediane
Back
Top