Need help with yamaha 4.3

[Whitetrash443]

I just purchased a 91 chaparral. It has the yamaha 4.3 vortec. The block is cracked my quess is from not winterizing it correctly. being a first time boat owner I'm not sure what will switch over and what will not. I ran the block numbers and it was a gm block. My question is what motor out of what year truck will fit mine? The motor was rebuilt a year and a half ago the heads and cam look great. Could I reuse? Any special head gaskets etc.I can do the work just need the knowledge on parts I only paid 700 for boat and trailer and would like to keep my expenses minimal. Any help would be appreciated thanks in advance.

 

[Bondo]

I only paid 700 for boat and trailer and would like to keep my expenses minimal.

Ayuh,...... Welcome Aboard,..... In All honesty, part out the Yamaha parts off yer hull,..... Ya should turn a profit,...

Then take that money, 'n buy a runnin' boat with a Mercruiser or Volvo driveline,.....
Or,...
Buy a rotten hull with a runnin' Mercriser or Volvo driveline in it, junk it, 'n put that driveline into the hull ya got,.....

Minimal expense, 'n a Yamaha driveline ain't gonna work out in the long run,.....

 

[Whitetrash443]

Yea so I've been reading the same. I'd hate to get rid of the boat I just got its in real good shape body and structural wise. I'm going to give it a long shot and purchase a block use my heads etc. Is the yamaha the same block and everything as the mercruiser 4.3 no?

 

[Bondo]

Ayuh,.... The easiest replacement is a Long Block crate motor for a 1991 Chevy truck,....

The 4.3l went through quite a few changes durin' it's run,....

Most all are adaptable, but startin' with a like vintage keeps things simple,.....

All of 'em, Yamaha, Merc, OMC, 'n Volvo are GM Long Blocks,....

 

[Swampmouse2]

WT,
I have to agree with Bondo on this. I bought a 92 Monterey last summer with the Yamaha 4.3, and it was a great running boat. Now that I have an issue, I cant hardly find a mechanic that will touch it, and parts are even harder to come by, and when you can find them (Yamaha parts that is), they are the prices of gold...literally. I can tell you that thanks to Capt. Ken, the recirculating water pump - the one that would be on a car engine - is a regular old chevy marine water pump. I called him about a week ago to buy one for my boat, and he said it was a plain old chevy marine pump.
If I had that motor, I would do exactly what Bondo said, and part that sucker out. Look up what the exhaust manifolds on that motor cost, and you will see what I mean. You'd get all your money back right there.
Sm

 

[Whitetrash443]

I understand the outdrive is yamaha but what makes the engine a yamaha? Just the exhaust manifold? I have been in numerous amounts of these engines on a car.l and to the naked eye it looks like the same infernal. I know the marine cam but my question is what makes it a yamaha and the difference between it and a truck motor? I can get my hands on a yamaha outdrive in the same county I live in I just have to take the crap boat it comes with but if I can get the boat and trailer wirh the drive compinents for 500 why not have spare parts! Like I said I'm a new boater first one for me just very curious. I do appreciate yalls input on the situation.

 

[Bondo]

but my question is what makes it a yamaha and the difference between it and a truck motor?

Ayuh,.... Ya gotta figure out the differences between a Bare Block, Short Block, Long Block, 'n Bobtail motor,....

Everything beyond the Long Block configuration is Yamaha,.......

 

[Whitetrash443]

I purchased a used block today. The motor in the boat had been reolaced and rebuilt with a motor from 96 up to 03 if I'm not mistaken. Im going to attempt to put it all back together and see what I've got. The heads on my motor were mint on one of the valves it has very little pitting on the bottom. Stems and edges look great. The minor pitting on the bottom should be ok as long as the valve seats correct? The motor was rebuilt run one time not winterized and the block cracked on both sides at the coolant passages. Reusing my heads good or bad idea (

 

[Whitetrash443]

I do appreciate yalls comments. I have one more I know the water pumo of course there is another pumo on the bottom right I assume a fresh water pump? If turns but has good amount of friction behind it. Is that normal? It has no pully play and the bearings seem ok just wondering if it should be so hard to turn. Thanks in advance for the comments

 

[Bondo]

If turns but has good amount of friction behind it. Is that normal?

Ayuh,... That's the raw water pump that pulls water from the lake, it has a rubber impeller that needs to be replaced every couple of years,....

Yes, the rubber impeller drags, especially without water to lube it,....

 

[Whitetrash443]

bondo thanks bud, installing the cam and will hopefully have everything finished up this evening. hoping all goes well and i can get this thing on the water. i will keep yall posted

 

[Whitetrash443]

ok i went to pull the pulley off of the raw water pump and bent it. my question is where to get a new pulley and do i specifically need a raw water pump if i dont run in brackish or salt water?

 

[triman]

Yes you do need the raw water pump. This supplies all the coolant to be circulated around the engine. Without it you'll definitely be doing a parting out of the molten remains.
The aftermarket service book has details on most of the maintenance operations, including the cooling system and the 2 pumps.
The Yamaha original raw water pump, if available, will be bloody expensive and is only a rebadged Sherwood R991 pump.
The replacement bits, if needed, are; Impeller Kit: 09959K
Minor Repair Kit:
Major Repair Kit: 18655
All Sherwood numbers.
hope this helps.

 

[Whitetrash443]

yea i cant find just the pulley. id hate to spend $532 on the whole pump when all i need is the pulley but they dont sell just a pulley they want to sell you the whole damn pump. i only paid 700 for the boat im ready to park it in the back yard and watch it rot. i did put a new block in it runs good just no pump

 

[Bondo]

i only paid 700 for the boat im ready to park it in the back yard and watch it rot.

Ayuh,.... Part it out, 'n turn a Profit, then buy a Merc or Volvo drive, Chevy powered boat,.....

Lotsa folks are tryin' to get one more lap outa the few Yamahas there are left out there,....

 

[Whitetrash443]

ok so i got everything in. iam having ahorrible time finding number 1 on dist. cap and how to set the dist. any help would be great.

 

[Antax]

Don't get to caught up in the boat part of the engine. It's still a Chevrolet 4.3L V6.

It helps to have an extra hand with this.

Find top dead center on the compression stroke:
1 Turn the crank until the timing mark on the harmonic balancer is 180 degrees of the timing mark on the engine.
2 Remove the spark plug from the number 1 cylinder
3 Put your finger over the spark plug hole and turn the crank until the timing mark on the balancer matches up with the mark on the timing mark on the engine

If you felt pressure and air coming out you were on the compression stroke and when the timing marks line up your done. If you didn't feel compression your were on the exhaust stroke. Turn the crankshaft another full turn and now your done.

Once you have top dead center on the compression stroke remove the distributor cap and the rotary button should be pointing to the front of the engine. If not remove the distributor and rotate the button until it points to the front and reinstall it.

This also may help a little...

 

[Bondo]

iam having ahorrible time finding number 1 on dist. cap

Ayuh,..... It don't Matter, so long as it's the post the rotor is pointin' at, at TDC, compression stroke,.....

The order is Critical, where #1 is, is Not,.....

 

[Antax]

Ok, sorry but I gotta ask. When your talking to someone do you always start out with "Ayuh"?

 

[Bondo]

Ayuh,.... Unless it's a Nope kinda question,....