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Replaced motor.... Help!!!!

C

chrisjpb

New member
So I'm going to preface this with.... I'm not a mechanic, but have accomplished some pretty cool automotive builds. I landed my very first boat, a 2006 SeaRay 205 Sport, for 2500 bucks with a blown motor. It was originally the 5.0 mercruiser. I had a 5.7 vortec Chevy sitting in the garage that was freshly built for a different project but decided to drop it in the boat since it was already on hand. Swapped out some parts from the 5.0 and got brand new exhaust manifolds. Got the motor running great. Idles like a champ, revs beautifully with the drive disengaged. Put it in gear and take off and I'm maxing out at about 2200 RPMs at 15-20 mph depending on with or against the current in the river we're testing in. It has a 14 1/4 x 21p three blade aluminum prop and the factory alpha drive. Where can I possibly start to figure out what's keeping us from even getting on plane, much less riding like it should?
 
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chrisjpb said:
.................. I had a 5.7 vortec Chevy sitting in the garage that was freshly built for a different project.
I decided to drop it in the boat since it was already on hand.
Was this 5.7L Vortec purpose built for automotive use or for marine use?

Swapped out some parts from the 5.0 and got brand new exhaust manifolds............... Put it in gear and take off and I'm maxing out at about 2200 RPM at 15-20 mph
First off, do not continue using the boat under those conditions.
Depending on what the issue is, you may damage this engine.


It has a 14 1/4 x 21p three blade aluminum prop and the factory alpha drive.
Is this the same drive and propeller that the 5.0L was in front of?

Where can I possibly start to figure out what's keeping us from even getting on plane, much less riding like it should?
I think that we first need to know what the 5.7L Vortec's purpose build was!

Also, which ignition system are you using on the 5.7L Vortec engine?
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RicardoMarine said:
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DO NOT USE THIS POST. IT HAS NOTHING TO DO WITH YOUR PROBLEM. As usual!



1. What is your speed (MPH)? With a 5.7 in a 20 ft boat you should be capable of 50+ MPH.

2. If you are reaching that speed then the tachometer may be the issue. If this is the issue, There is a three position switch on the back of the tach. 4Cyl, 6Cyl, 8Cyl.
Confirm on 8Cyl. if it is, switch to other selections and then back to 8Cyl. See if that changes RPM reading. (Can be done out of water)

3. If not Tach issue then you need to confirm outdrive gear ratio. It should be 1.50/1.47 to 1. If the outdrive is no badly aged you should be able to read this as shown in picture below. Otherwise you will need to manually spin drive input shaft and count propeller rotations. (drive will need to be removed from boat)

If your gear ratio is not 1.50-1 or 1.47-1 then that may be your issue.


Serial number.jpg


If all this is OK, Then you may have a fuel or timing advance issue.
Is engine carbed or EFI?
 
I have a 2004 Sea Ray 200 sport and did a similar project, bought it with a cracked 4.3 and swapped in a 5.0. Nice size boat for family fun.

What blew the original engine ? Cracked or was it detonated by running lean?

per jacks comments verify the tach is accurate.

What cam is in the replacement engine. Needs to be of marine, or truck/ towing / RV type grind to work in this application, if it is a typical car cam you likely won’t have the low end torque to push a boat through the water and allow engine rpms to increase. Car cam can also have overlap such that water reversion in exhaust can be an issue .

what carb is on it? Is it the 2 bbl off the 5.0? What do they plugs look like. Might be somewhat lean if it is jetted for a 5.0.

what ignition system are u using? Assume you brought the thunderbolt V off the original engine over? If this is operating correctly you should be ok if it is working properly. Should give you about 28-30 degrees total advance at like 2500 rpms or so. Verify you are getting advance and that something simple like leaving the timing in base mode (grounding wire on Tbolt V ) isn’t occurring. Can check with timing light but might need a timing tape on the balancer to see the advance in degrees.

Sea Ray likely shipped your boat with a 1.62:1 drive, while normally a 5.7 would have a 1.47 or 1.5 ratio. This steeper gear by using the original drive would only increase the rpm the engine will turn. In my swap I kept the factory 1.81 V6 ratio drive, I just had to step up in pitch from a 19” to a 21 “ pitch prop. Given I can swing a big biting rev4 prop with a 5.0 in basically the same boat you should have no issue.
 
IF you have the Thunderbolt ignition you have to time it--over and over, if necessary--until you have the 8 or so degrees advance AND it's running at 700 rpm at the time. The circuitry bumps the timing at around 1,000 rpm and can trick you.

Something else to consider, but if that motor has a "hot" cam you have to get out the wrenches! As stated above, a truck/ RV cam is what's needed here since torque moves the boat, not horsepower.

Jeff
 
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kghost said:
DO NOT USE THIS POST. IT HAS NOTHING TO DO WITH YOUR PROBLEM.
I beg to differ. I asked some specific questions that may be helpful.

1. What is your speed (MPH)?
See post #1 again.


If this is the issue, There is a three position switch on the back of the tach. 4Cyl, 6Cyl, 8Cyl.
Confirm on 8Cyl. if it is, switch to other selections and then back to 8Cyl. See if that changes RPM reading. (Can be done out of water)
See post #1 again regarding "maxing out at about 2200 RPM at 15-20 mph".
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fastjeff said:
IF you have the Thunderbolt ignition you have to time it--over and over, if necessary--until you have the 8 or so degrees advance AND it's running at 700 rpm at the time. The circuitry bumps the timing at around 1,000 rpm and can trick you.
Jeff
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Tbolt V needs to be put in base mode to set the timing. There is a bullet connector that is capped in the harness by the shift interrupt. You ground this before starting the engine. Can easily set it to 10 deg BTDC or whatever the engine calls for. Remove the ground and restart the engine it is out of base mode. Great ignition system with a very hot spark, only bump wrap is if u need to replace ignition module it’s like $500-600. I bought a spare on eBay for $150
 
Chris has not been back to his thread here as to verify which ignition system he is using.
Hopefully he is using the Marine system, and he understands how to set it up.
 
The motor was originally the 5.0 with a 2bbl Rochester style carb on it. We put in a 5.7 with a 650 Edelbrock carb on it. Automotive, not Marine, temporarily until we get a marine carb for it. All the distributor, coil, alternator, etc was pulled from the 5.0 and moved to the new engine. How can I identify what type of ignition system is there?
I know the mechanic that timed the motor timed the advance without putting in any kind of "base mode".
The original engine was bad because salt water got into the cylinders because of bad exhaust manifold and the owner let it sit with that salt water in it for over a year.
 
chrisjpb said:
The motor was originally the 5.0 with a 2bbl Rochester style carb on it. We put in a 5.7 with a 650 Edelbrock carb on it. Automotive, not Marine, temporarily until we get a marine carb for it. All the distributor, coil, alternator, etc was pulled from the 5.0 and moved to the new engine. How can I identify what type of ignition system is there?
I know the mechanic that timed the motor timed the advance without putting in any kind of "base mode".
The original engine was bad because salt water got into the cylinders because of bad exhaust manifold and the owner let it sit with that salt water in it for over a year.
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google thunderbolt V ignition systemor post some pics what you’ve got, but if it is the OEM ignition that came with your 220 hp 5.0it will be the thunderbolt V with the ignition module on the exhaust elbow.

if your mechanic didn’t set it in Base mode and rotated the distributor to 10 degrees you will have very retarded timing as the module will be pushing some advance even at idle.

link for setting timing it’s easy to do with a basic timing light. http://download.brunswick-marine.co...n/mercruiser/gasoline/861328-1/8613281_4b.pdf

what camshaft is in the engine? If you have a mild hot rod automotive can you risk reversion and pulling water into the cylinders through the exhaust. If it was a truck crate motor your probably ok with this cam as is.

get edlebrock 1409 marine carb as automotive ones are a fire and explosion risk when used in a marine closed engine compartment. a couple other thoughts - make sure any modifications to the fuel line were done with marine A1 rated hose or hard line .. Also if you look for the throttle brackets used on a357alpha mercury crate engine it will adapt your throttle linkage and mount your slave solenoid like on the throttle bracket for your 2 bbl that won’t fit your edelbrock.
 
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I landed my very first boat, a 2006 SeaRay 205 Sport, for 2500 bucks with a blown motor.
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(shakes head in disbelief) Please next time you go shopping stop here first and ask the forum.
 
o2batsea said:
(shakes head in disbelief) Please next time you go shopping stop here first and ask the forum.
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We knew the motor was blown, I already had a built 5.7 so all in we are still under 5 grand so far in a pristine 21 ft sea ray so I'm not sure how I went wrong there once we get this issue ironed out.
 
Dieter said:
google thunderbolt V ignition systemor post some pics what you’ve got, but if it is the OEM ignition that came with your 220 hp 5.0it will be the thunderbolt V with the ignition module on the exhaust elbow.

if your mechanic didn’t set it in Base mode and rotated the distributor to 10 degrees you will have very retarded timing as the module will be pushing some advance even at idle.

link for setting timing it’s easy to do with a basic timing light. http://download.brunswick-marine.co...n/mercruiser/gasoline/861328-1/8613281_4b.pdf

what camshaft is in the engine? If you have a mild hot rod automotive can you risk reversion and pulling water into the cylinders through the exhaust. If it was a truck crate motor your probably ok with this cam as is.

get edlebrock 1409 marine carb as automotive ones are a fire and explosion risk when used in a marine closed engine compartment. a couple other thoughts - make sure any modifications to the fuel line were done with marine A1 rated hose or hard line .. Also if you look for the throttle brackets used on a357alpha mercury crate engine it will adapt your throttle linkage and mount your slave solenoid like on the throttle bracket for your 2 bbl that won’t fit your edelbrock.
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Ok, this helps a lot and I will check that. We timed it to 10 degrees but wasn't aware of the base mode, as I haven't seen anything about that in the manuals that came with the boat. I will use your link to back and recheck timing this week and hopefully go test again on saturday! Hopefully it is something this simple.

Firing order is correct, we went back through that, and it is a Truck crate cam.

We plan on adding an edelbrock marine carb, i just already had a 650 edelbrock and intake here to test with and finish the main part of the build. Going to put marine intake and carb on before we get in the salt. All fuel lines were original hard line except for 5 inches of regular fuel line to adapt to the temporary carb. I will get some A1 hose for when we switch carb back out. Thanks for that advice! I wish I had found this forum before I ordered throttle brackets from Summit that we still had to modify. I will try to find the ones you mention to put on later, cause I really do want it to be right when its all said and done, and that slave with circuit breaker is definitely not how I want it to be done right now.
 
So, a little more information and update. Went out to the boat today but it was late and getting dark so I couldnt get decent pictures. I am pretty sure there is something wrong or missing. I found the purple and white wire coming out of the DENSO module mounted to the exhaust elbow. but it goes from the elbow into a loom, and I keep reading in the manuals theres supposed to be some type of lead or other end to use the jumper cable to ground? I connected a probe to that wire at the module and grounding does nothing to the timing. We double checked with the timing light and then ungrounded and rechecked current timing. At idle the motor was sitting at 10 BTDC, and it didn't jump around at all which I have read should be indicative of a thunderbolt 5 igniton, that it should be kind of erratic when not grounded as it adjusts. we revved up to 2400 RPM and it is still sitting dead on 10 BTDC so it isn't advancing at all.
My understanding after researching is that this module requires input from a knock sensor on that pur/white wire to adjust? but I get no signal on that wire at all while motor is running.

The Ignition Module I have is this one, pic stolen from an ebay post, and there is no secondary module attached with it like I've seen in some other photos.
Ignition Control Module.jpg

I found this diagram of the TBV ignition system and basically everything in red I don't see though maybe its just somewhere Im not looking? the purple and white wire just goes into the engine harness loom
Ignition Diagram annotated.png
 
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o2batsea said:
note that in that diagram, c and d are mislabeled. That is, box c is identified in chart d and vice versa.
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say what?
Ok got it.............But this may add confusion as C and D have NOTHING TO DO WITH ISSUE
 
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As outlined in post 7 - the bullet connector is by the shift interrupt which is mounted to the other elbow opposite where the denso labeled ignition module will be a wire with a small plastic plug in it coming out of the harness jumper this to ground before starting engine. This is 13 in your diagram but will be located in harness on other side of engine by shift interrupt. That drawing is a tad misleading

knock sensor is something totally different and has nothing to do with setting base timing, and your like most 5.0 carved motors didn’t have one
 
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RicardoMarine said:
O2batsea is simply adding clarification.
Do not assume that others will become confused.
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Who asked you for your useless opinion!
Where were you with your product specific "expert" opinion and images from YOUR vast Mercruiser manual selection?

Again, usless spew from PCR.
 
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Dieter said:
As outlined in post 7 - the bullet connector is by the shift interrupt which is mounted to the other elbow opposite where the denso labeled ignition module will be a wire with a small plastic plug in it coming out of the harness jumper this to ground before starting engine. This is 13 in your diagram but will be located in harness on other side of engine by shift interrupt. That drawing is a tad misleading

knock sensor is something totally different and has nothing to do with setting base timing, and your like most 5.0 carved motors didn’t have one
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Which drawing? The one from the Mercruiser Manual? Or the one he posted that he acquired from the internet?
 
kghost said:
Which drawing? The one from the Mercruiser Manual? Or the one he posted that he acquired from the internet?
Click to expand...
On the OPs drawing where he crossed out in red. On my harness this is physically located right next to the connection for shift interrupt and lays on top of intake. I think OP was looking for it between the module and the distributor
 
If that module is mounted on the elbow then someone got creative because that module is neither TB IV or TB V This is TB V
Post some pics of what YOU have on the motor
 
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Bt Doctur said:
If that module is mounted on the elbow then someone got creative because that module is neither TB IV or TB V This is TB V
Post some pics of what YOU have on the motor
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my TB V was mounted on the elbow from the factory just behind oil fill second photo uploaded with better resolution ...
 

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It is tough to understand exactly how he is doing the timing. He does NOT specifically say he is jumping the base timing connector before starting the engine as written and advised.

But if he is doing it correctly and the timing is staying at 10*btdc all the time with no advance or retard then his timing/ignition control module may be bad.
This would tie into not achieving max RPM.
 
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