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Test running engine removed from boat

mpt

mpt

Contributing Member
I just renewed top end parts on my 4.3 ltr V6. Now it's sitting on a temporary motor base I built to test the engine. I want to make sure everything is running good before I reinstall it back into the boat. My questions are mainly electrical:
a) Since It is unplugged from the boat wiring harness, how do I get power to the coil from my battery.
b) Do I have to run the alternator?
c) how much garden hose water pressure should I maintain when it's temporarily tied in to the cooling system(raw water)?
d) Is there a link I can read about this process?
 
a) just run a hot wire directly from a battery, or from the starter hot side lug.
b) no, the coil will fire from the hot supply until the battery craps out.
c) there is no pressure building if the water is just flowing thru. If the thermostat is installed it will build up some until it opens, but shouldn't do any harm. Don't need to have the water going full blast.
d) dunno.
 
I just renewed top end parts ..................... My questions are mainly electrical
Click to expand...
If this involved cylinder head work ONLY, then you have no issues with piston rings. So running on the temporary base poses no issues that I can see.
It would poses an issue if you were attempting to seat new piston rings and intended to run for a long duration! For this, we need to properly load the engine.


a) What year/which ignition system? If this uses an EST system, use caution as to how/what you power up!
Your OEM engine harness will no doubt be installed on the engine......... so look at the hull harness schematic, and your ignition system......, and power up that which is necessary.

b) Depends on how the alternator is regulated. If externally regulated, I believe that you can spin it as long as the field is not excited. However, if your engine harness is installed and connected, this should take care of itself! Again, as long as you power up via the OEM harness.
NOTE: you make no mention of year model. If by chance your helm has an Amp Meter (not volt meter), then the engine/hull harness will take the charge circuit forward and back again. This must be "looped" in order to complete the charge circuit while you are test running....... but again, you make no mention of this!

c) No excessive pressure, only volume!
Is this Raw Water cooled, or does it have a Closed System?
A raw water system thermostat should have a small air bleed hole in it. This purges air from a dry cooling system upon start-up. (we do not want sudden cold water entering a hot cylinder block/heads)
Best to shut down water supply just prior to shutting the engine down.

d) I doubt you will find any Pros suggesting a "how to", as there are some inherant risks in doing this.... and too many systems to cover in one video! However, I just Google'd "test running marine engine", and yes, there are some videos. I cannot suggest that these guys are offering a good DIY'r Joe demonstration!
One video shows powering the ignition coil directly....., but makes no mention of the ignition system. A less than responsible suggestion, IMO.
He also attaches full garden hose water pressure/volume to the sea water intake hose! The risk in this, will be over-supplying water that may become introduced into an open exhaust valve while the engine is not running!
Use Caution and common sense..... you'll do just fine!

Again, Best to shut down water supply just prior to shutting the engine down.


.
 
RicardoMarine said:
If this involved cylinder head work ONLY, then you have no issues with piston rings. So running on the temporary base poses no issues that I can see.
It would poses an issue if you were attempting to seat new piston rings and intended to run for a long duration! For this, we need to properly load the engine.


a) What year/which ignition system? If this uses an EST system, use caution as to how/what you power up!
Your OEM engine harness will no doubt be installed on the engine......... so look at the hull harness schematic, and your ignition system......, and power up that which is necessary.

b) Depends on how the alternator is regulated. If externally regulated, I believe that you can spin it as long as the field is not excited. However, if your engine harness is installed and connected, this should take care of itself! Again, as long as you power up via the OEM harness.
NOTE: you make no mention of year model. If by chance your helm has an Amp Meter (not volt meter), then the engine/hull harness will take the charge circuit forward and back again. This must be "looped" in order to complete the charge circuit while you are test running....... but again, you make no mention of this!

c) No excessive pressure, only volume!
Is this Raw Water cooled, or does it have a Closed System?
A raw water system thermostat should have a small air bleed hole in it. This purges air from a dry cooling system upon start-up. (we do not want sudden cold water entering a hot cylinder block/heads)
Best to shut down water supply just prior to shutting the engine down.

d) I doubt you will find any Pros suggesting a "how to", as there are some inherant risks in doing this.... and too many systems to cover in one video! However, I just Google'd "test running marine engine", and yes, there are some videos. I cannot suggest that these guys are offering a good DIY'r Joe demonstration!
One video shows powering the ignition coil directly....., but makes no mention of the ignition system. A less than responsible suggestion, IMO.
He also attaches full garden hose water pressure/volume to the sea water intake hose! The risk in this, will be over-supplying water that may become introduced into an open exhaust valve while the engine is not running!
Use Caution and common sense..... you'll do just fine!

Again, Best to shut down water supply just prior to shutting the engine down.


.
Click to expand...

Rick, first I want to thank you for your time spent in writing your reply!
My engine is a '96 "NC" model 43GSPNCA that powers a Volvo/OMC Cobra stern drive. It is a crossover year engine, with a stamped steel oil pan, 4BBL carb, raw water cooling, and electronic ignition. I only replaced the parts on top of the motor that relates to the cooling system- rebuilt heads. intake (Volvo) and exhaust manifolds(Barr), risers(Barr), circulating pump, sea pump impeller, and thermostat housing. Some day I will understand what NC, GS, GL, and GI models represent? As far as what type of ignition system, all I can say is that it's electronic. I have the Volvo workshop manual(pn#7788887-3) for electrical & ignition, the schematics are fairly easy to understand, but so far I can't read anything in it about hot wiring engine for test running.
 
mpt said:
Rick, first I want to thank you for your time spent in writing your reply!
My engine is a '96 "NC" model 43GSPNCA that powers a Volvo/OMC Cobra stern drive. It is a crossover year engine..................
but so far I can't read anything in it about hot wiring engine for test running.
Click to expand...
You are welcome!

FYI; by 1996, this would be all Volvo Penta. V/P bought out OMC in 1993. So I am not sure what you mean by "cross over" year. You may see a fuel filter base unit, or a logo, saying OMC on it........, but this is a heavy Volvo Penta influence "Cone Clutch" design drive by 1996.

As for "hot wiring", just power the engine harness as the hull harness would. I'd not take anything out of the loop, so to speak!
You will not have engine temp or oil pressure, but the engine won't know the difference unless you tell it! :D

.
 
Rick... aka Ricardo-
When you suggest turning the garden hose off before shutting off engine, then I should by-pass the external sea pump during operation for fear of damage to the brand new impeller I installed in it.
 
If you are hooking the garden hose up directly to the engine you need to shut the water off before you shut the engine down so you don't fill the cylinders with water. I would run the hose into a bucket and let the raw water pump pull from the bucket, then you don't have to worry about turning off the water before the engine shut down. Just make sure the bucket is below the engine. If it is above it will siphon the water from the bucket after the shut down.
 
Docksidemarineservices said:
If you are hooking the garden hose up directly to the engine you need to shut the water off before you shut the engine down so you don't fill the cylinders with water. I would run the hose into a bucket and let the raw water pump pull from the bucket, then you don't have to worry about turning off the water before the engine shut down. Just make sure the bucket is below the engine. If it is above it will siphon the water from the bucket after the shut down.
Click to expand...
The water level in the bucket should be below water outlet in raisers, which will be about the same as waterlevel when installed in the boat.
 
mpt said:
Rick... aka Ricardo-
When you suggest turning the garden hose off before shutting off engine, then I should by-pass the external sea pump during operation for fear of damage to the brand new impeller I installed in it.
Click to expand...
Not necessarily! If you chose to supply cooling water via the sea water pump, the impeller will be "wet". This will run for several seconds without any risk of impeller damage. It takes only fractions of a moment to turn the garden hose supply OFF, followed by ignition shut down.

It would be a "dry" impeller that would be at risk..... not necessarily a residually "wet" impeller...... at least not during a very short run-time.


Docksidemarineservices said:
If you are hooking the garden hose up directly to the engine you need to shut the water off before you shut the engine down so you don't fill the cylinders with water. I would run the hose into a bucket and let the raw water pump pull from the bucket, then you don't have to worry about turning off the water before the engine shut down. ...............
Click to expand...
Chris sums this up perfectly!

Either method should work for you! The bucket sounds like the best option, IMO.

.
 
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