V6 3.8L 1981 + 800 gearcase problems

[max3005]

(I'm from Switzerland on Lake Geneva, please excuse my bad english)

Hello,
I have a 1981 Starcraft motorboat with an 1981 OMC 3.8L V6 motor and an OMC 800 gearcase.

During this winter I had changed the upper and lower gearcase (buy "new" ones on eBay) and i have changed the camshaft and some other pieces (gaskets, etc) after severals problems during last season.

I recently have put the boat in the water to test all the stuff.

In neutral, the motor runs great, no problem, no overheating, nice accellerations, everything OK. So I decide to go out of the harbor to test the forward and reverse.

First, in forward, the motor had very irregular RPM like something is "restraining" it. After a few minutes, this problem disapearred (without noise...) and the boat runs great in forward too.

After about 20 minutes of nice boating in full speed (4400 RPM), the motor starts to overheat (about 220 ?F), I dont know why, and brutally stop (it was in 4000 RPM and then stopped). After some difficulties I can go back to the harbour.

At the harbour, in neutral, now the motor is doing strange noise, I check the oil level it's OK. The RPM are very irregular, like the first time I put it into forward. But the cooling system is OK, the motor stays at about 155 ?F. It's really like something in the gearcase is restraining the motor... So I think I don't have broke the impeller or something like that.

I suppose the noise is coming from the upper gearcase. The noise is louder when you are at the back of the boat than when you are in the engine compartment.

When I tilt up the gearcase, the noise is still here but louder ==> does it come from exhaust ?

Do I have broke a piece in the gearcase during overheating ? Can you suggest me some points to check or some tests to do to localise the problem ?

Thanks, Max

 

[Howard Sterndrive]

Re: V6 3.8L 1981 + 800 gearcase problems

your English is excellent
start with a compression test of the engine.
then drain fluids from the upper and lower units to look for metal in the oil. need to figure out which is seizing up - engine or drive if either...
a lean fuel mixture -running out of fuel can feel like the engine is seizing from the driver's seat

When I tilt up the gearcase, the noise is still here but louder ==> does it come from exhaust ?

the ball gears will normally get very noisy when tilted. Your drive should never be tilted with the engine running. Only run the engine with the drive all the way down.

What camshaft did you use? Edelbrock 2112?
I'd be interested in your method of installing the distributor when the engine was reassembled too...that 229 chev is tricky like no other engine for finding #1 on the distributor

 

[max3005]

Re: V6 3.8L 1981 + 800 gearcase problems

your English is excellent
start with a compression test of the engine.
then drain fluids from the upper and lower units to look for metal in the oil. need to figure out which is seizing up - engine or drive if either...
a lean fuel mixture -running out of fuel can feel like the engine is seizing from the driver's seat

Thanks for your answer !
I will quickly drain the oil from the gearcase to see if there is water, metal, etc? But If there is water (or metal), why ? I buy the upper and the lower part on eBay, they were "rebuilt" and "pressure tested". So if water can go in the gearcase, I assume it's problem in the mounting? I have another "symptom" of that : steering is much more harder than before. Can it be possible that water is coming in and hard steering if I have tighten too hard the lower part to the upper part ?

I don't think it's a problem of lean mixture. At high RPM, carburetor's jet are fixed, I can't adjust it (my carb is a Rochester 2-Jet, 2GC or 2GV i don't exactly know). At idle, there is two adjustment screw. My spark plugs are black so I believe my mixture is too rich, not too lean. I have problems with the automatic choke? but it's not my main problem actually.

the ball gears will normally get very noisy when tilted. Your drive should never be tilted with the engine running. Only run the engine with the drive all the way down.

Thanks for the advice ! In my manual they said not too run the engine with drive up more than 1500 RPM...

What camshaft did you use? Edelbrock 2112?
I'd be interested in your method of installing the distributor when the engine was reassembled too...that 229 chev is tricky like no other engine for finding #1 on the distributor

I don't know which Camshaft it was exactly. I bought it in a french company who is like the only supplier of OMC parts I have found in whole Europe. They said it was a "replacement camshaft" and effectively it was not exactly the same as the original.

For the distributor it's very simple : there is a mark on the harmonic balancer pulley and a "rake" (i don't know the exact word) fixed on the engine. Basically it's too adjust the timing of the ignition. But I know that when the mark is aligned with the rake, cylinder 1 or cylinder 4 is at TDC (ignition order is 1-6-5-4-3-2). So I turn the crankshaft "by hand" to align the mark with the rake, and i put a wire in the cylinder (via the spark plug hole) # 1 (to see if it was at TDC or at BDC). If it was not at TDC, I have turned the crankshaft one more turn. When cylinder #1 is at TDC (approximatively), i put the distributor back in place, look at the position of the rotor, put back distributor coil and plus spark plug wire (coming from cylinder 1) to the position of the rotor, and put the others wire in order 1-6-5-4-3-2. It has perfectly work. After that of course I have adjusted the advance of the timing.

 

[Howard Sterndrive]

Re: V6 3.8L 1981 + 800 gearcase problems

If there is water (or metal), why ? I buy the upper and the lower part on eBay, they were "rebuilt" and "pressure tested". So if water can go in the gearcase, I assume it's problem in the mounting? I have another "symptom" of that : steering is much more harder than before.

eBay is hit and miss. humans can mess up. ... when you install the upper, you need to shim the top exhaust cover to provide the proper clearance for the upper to "float" in the gap - I think it is .020-.030" and there are shims on top of the upper that hold the cap up- should fix your steering

I don't think it's a problem of lean mixture.

I wasn't referencing the carb- I was thinking of fuel pump or anti-siphon check valve at the fuel tank running you out of fuel...or a plugged fuel tank vent

For the distributor it's very simple : there is a mark on the harmonic balancer pulley and a "rake" (i don't know the exact word) fixed on the engine. Basically it's too adjust the timing of the ignition. But I know that when the mark is aligned with the rake, cylinder 1 or cylinder 4 is at TDC (ignition order is 1-6-5-4-3-2). So I turn the crankshaft "by hand" to align the mark with the rake, and i put a wire in the cylinder (via the spark plug hole) # 1 (to see if it was at TDC or at BDC). If it was not at TDC, I have turned the crankshaft one more turn. When cylinder #1 is at TDC (approximatively), i put the distributor back in place, look at the position of the rotor, put back distributor coil and plus spark plug wire (coming from cylinder 1) to the position of the rotor, and put the others wire in order 1-6-5-4-3-2. It has perfectly work. After that of course I have adjusted the advance of the timing.

wow - you need to go and check that - it is NOT that simple - I wasn't kidding when I said that 229 is like no other engine for timing
you have a few wildcards in your procedure.. beside needing the cylinder at TDC compression (not just TDC),
Have a look at page 5 of this bulletin - you need to pay attention to which specific lobe of the distributor cam your points arm is sitting against at #1 TDC
http://www.boatfix.com/merc/Bullet/83/83_09.pdf
otherwise, detonation can damage the engine
that's weird engine - never assume it's just like any other V6...it only looks like a 4.3 on the outside

that cam thing is a concern too - I hope they didn't sell you a 4.3 camshaft
got the number? really NEED to check that out
You coulda got an Edelbrock 2112 kit for $129 from Jegs or Summit - identical grind to the OMC 3.8 229 chev marine cam

an automotive 229 cam will rob you of about 50HP...the 1980's car cams were serious smog era lumps..
170HP in a boat - 110HP in a car, and the only real difference was the cam..

 

[max3005]

Re: V6 3.8L 1981 + 800 gearcase problems

eBay is hit and miss. humans can mess up. ... when you install the upper, you need to shim the top exhaust cover to provide the proper clearance for the upper to "float" in the gap - I think it is .020-.030" and there are shims on top of the upper that hold the cap up- should fix your steering

Yes i just have found this in my manual I will check that too. My manual said :

7. Measure the gap between the exhaust cover and upper gearcase cover with a feeler gauge.
8. Raise the upper gearcase as much as possible and remeasure the gap. The difference between the 2 measurements should not exceed 0.005-0.015 in.
9. Install the shims required to bring the up-and-down play within specifications. Shims are installed on the steering post boss in the top center of the upper gearcase.
10. Install a new O-ring on the exhaust cover spline. Install the exhaust cover and tighten fasteners to specifications (Table 1).

I don't exactly understand the procedure. I have to measure the gap between top of upper gearcase and the exhaust cover. OK. Then I have to measure it when the upper gearcase is "raised" ? what does that mean ? Thanks for help

I wasn't referencing the carb- I was thinking of fuel pump or anti-siphon check valve at the fuel tank running you out of fuel...or a plugged fuel tank vent

OK. I don't even think the problem is that because the fuel tank is full of fuel, and the engine has perfectly worked just before?

wow - you need to go and check that - it is NOT that simple - I wasn't kidding when I said that 229 is like no other engine for timing
you have a few wildcards in your procedure.. beside needing the cylinder at TDC compression (not just TDC),
Have a look at page 5 of this bulletin - you need to pay attention to which specific lobe of the distributor cam your points arm is sitting against at #1 TDC
http://www.boatfix.com/merc/Bullet/83/83_09.pdf
otherwise, detonation can damage the engine
that's weird engine - never assume it's just like any other V6...it only looks like a 4.3 on the outside

Thanks for that ! I will immediately check that. It was absolutely not mentioned in my manual (looks like my manual is not very good).

I imagine that if cylinder 1 was not at TDC-Compression, the motor would not have start ? If yes, how can I check if the cylinder is at TDC-Compression or not ?

that cam thing is a concern too - I hope they didn't sell you a 4.3 camshaft
got the number? really NEED to check that out
You coulda got an Edelbrock 2112 kit for $129 from Jegs or Summit - identical grind to the OMC 3.8 229 chev marine cam

an automotive 229 cam will rob you of about 50HP...the 1980's car cams were serious smog era lumps..
170HP in a boat - 110HP in a car, and the only real difference was the cam..

About the camshaft : i have found the informations about mine on the original package (lucky i have not throw it!) . It was originally sell by "Federal Mogul" under the number "CS-1030R".

The technical informations of Edelbrock 2112 (found on the web) are :
Duration Advertised : 270?Intake / 280? Exhaust
Duration @ .050" : 204? Intake / 214? Exhaust
Lift @ Valve : .420" Intake / .443" Exhaust
Lift @ Cam : .280" Intake / .295" Exhaust
Lobe Separation Angle : 112?
Intake Timing @ .050" : Open 5? ATDC, Close 29? ABDC
Exhaust Timing @ .050" : Open 44? BBDC, Close 10? BTDC

The informations of my camshaft are :
Duration @ .050" : 202? Intake / 213? Exhaust
"SAE" Duration : 269? Intake / 284? Exhaust
Lift @ Cam : .273" Intake / .273" Exhaust
Life @ Valve : .410" Intake / .410 Exhaust
Lobe CTRS : 111 Intake / 115 Exhaust
Lash : HYD.

@ .50 Cam Lift
Intake
BTC : 10-
ABC : 32
Exhaust :
BBC : 40
ATC : 7-

SAE J604
Intake
BTC : 16
ABC : 73
Exhaust
BBC : 68
ATC 36

I have exactly copy the informations on the package? I do not understand all of them! I'm not a professional? only a 19 years old student who want to have fun with his boat

The company said to me before I buy it that the camshaft is actually for the 3.8L. What do you think ? The values "looks like" to be approximatively the same, don't they ? Hope I do not have to do again all the replacement? In all the cases the company guaranteed me so in the case I have to replace it I can be (theorically) repaid for the cam?

Thanks a lot for your time and your answers!

 

[Howard Sterndrive]

Re: V6 3.8L 1981 + 800 gearcase problems

according to this: http://www.itacr.com/catalogos/sealed.pdf

the Federal Mogul 1030 cam is a 4.3L camshaft (262 cu. in.), not a 3.8L cam

sorry to break the news to you, but that engine will never run properly with that cam
in fact you will probably melt pistons under load....I'd be surprised if the engine can make 50HP with that cam anyways so probably not an issue - you could never get on plane

A 4.3 has a completely different pattern of pistons arriving at TDC than a 3.8 (229), so your valve timing is all out of whack
A 4.3 has a piston arriving at TDC every 120 degrees of crank rotation (like most V6's), but not the 229....the 229 has a piston arriving at TDC in this pattern: 108deg, 132 deg. , 108 deg., 132deg etc...

so the valves have to open at the correct time accordingly, and the spark plug has to fire at the right time too (thus the Mercruiser timing bulletin and odd shaped point cam lobe in the dizzy)

That's the thing with these Chevy 90 degree V6's.... they'll run and idle with the wrong cam, wrong distributor timing, (a 229 will actually run with a 4.3 distributor in - for a while) and then when you put them under load....all hell breaks loose... pistons melt...detonation breaks stuff.

 

[max3005]

Re: V6 3.8L 1981 + 800 gearcase problems

What a news !

I'm very surprised about this, because before overheating the boat goes nice, fast, i plane, no suspect noise, really perfect.

I hope the noise (and overheating?? ) don't come from melted pistons or something like you described. Do you think the problems I have described are similar to this kind of problems ?

In this case the only thing I can do is change my motor, right ? :facepalm:

I'll seriously ask this company who sell me this camshaft.

 

[max3005]

Re: V6 3.8L 1981 + 800 gearcase problems

Can you please help me too with that point ? Thanks

Yes i just have found this in my manual I will check that too. My manual said :

7. Measure the gap between the exhaust cover and upper gearcase cover with a feeler gauge.
8. Raise the upper gearcase as much as possible and remeasure the gap. The difference between the 2 measurements should not exceed 0.005-0.015 in.
9. Install the shims required to bring the up-and-down play within specifications. Shims are installed on the steering post boss in the top center of the upper gearcase.
10. Install a new O-ring on the exhaust cover spline. Install the exhaust cover and tighten fasteners to specifications (Table 1).

I don't exactly understand the procedure. I have to measure the gap between top of upper gearcase and the exhaust cover. OK. Then I have to measure it when the upper gearcase is "raised" ? what does that mean ? Thanks for help

 

[Howard Sterndrive]

Re: V6 3.8L 1981 + 800 gearcase problems

just shim it so you have that specified play - so the upper can float and the steering is un-clamped
more shims = more play
the correct amount of shims are probably just stuck by an oil film in the top of your old upper

You got way bigger problems though.