Questions about a test tank?

[eduardo kang]

I did a search and was able to turn up a bunch of posts about "test" and "tank", but only one pertaining specifically to a "test tank".<br />Not ever seeing a test tank before I was curious as to what size they usually are in order to properly simulate operating conditions. I have a few large containers available that will allow me to submerse my outboard (up to 100 gal.), but I have concerns. Is this big enough? Will the motor heat 100 gallons in a 1/2 hour?<br />I need to run my outboard for about 15 minutes at around 4200 rpms to duplicate whats happening on the water and I will need to locate a test prop to simulate a 14x17 prop (of course the test will not happen unless I procure a test wheel).<br />Does anyone have any experience running an outboard in a tank?<br />I'm a totally new to wrenching on outboards and want to learn. I have the OMC manual for my motor (2000 90hp ocean pro), so I'm off to a good start. I apologize ahead of time for any stupid questions.<br /><br />Here is the link to my original post..<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=028024 <br /><br />Thanks in advance for any replies..<br /><br />-e

 

[DHPMARINE]

Re: Questions about a test tank?

Test tanks vary in size.The one I use at the shop is roughly 5x5x5 (that's feet),and holds around 530 gallons.<br />I suggest you find the test prop and experiment .The test prop loads the motor,but doesn't agitate the water,as much as a prop.I think you need more than 50 gallons. But suggest 100 gallons may work.<br />Also heat isn't too much of a problem,as the exhaust bubble rises to the surface and escapes.<br />The problem is if these bubbles go back into the water intake on your lower unit.Now you are lacking h2o to the waterpump.Big tanks have baffles to help prevent this.<br /><br />DHP<br />Maybe diagnos your 'slow' problem in the water or on the trailer.

 

[eduardo kang]

Re: Questions about a test tank?

Thanks for the reply DHP...<br />After rethinking symptoms I'm going to check out the slow systom to verify the motor isn't exceeding 240* f. It very well could have and cooled to below 207* and that's when I was able to exceed 2500 rpms on my motor. <br />Another couple questions... I have a fluke 80TK therm module that I can connect to my 77 III, will a get an accurate temp reading if I touch the prob to my heads? (this is what I have http://www.testequity.com/products/935/ )An IR temp prob would be ideal, but I don't want to fork out the cash if I don't have to. If I am having a problem with my engine over heating, besides the t-stats and impeller, is there anything else to check?<br /><br />I think this weekend will be too early to to get a tank and test prop setup, so my plan is to run the boat until the problem occurs, have a 3-6 gallon test gas tank and hook that up to test out my fuel system. I that doesn't help, I'm going to do resistance test on the ignition components while the motor is warm, examine plugs, move coils to see if that changes the condition of the plugs, etc. If all of that stuff tests out fine I'm going to buy a peak vaoltage adapter for my VOM and use that to test further.<br /><br />Again, I apologize for all of the questions, I just want to make sure my logic in testing the motor isn't flawed. With my lack of experiance I could be misinterpreting what i think is a miss for something else..<br /><br />Thanks again,<br />-e

 

[DHPMARINE]

Re: Questions about a test tank?

-e,Fluke makes some great equipment.Your hand can tell you if you are at or near 200 degrees.With the motor not running (not sure if I need to use these safety warnings) place your hand on the top of each cylinder.It should be warm,but not that uncomfortable.If you quickly have to pull your hand away,you may be overheating.If you can keep your hand there,you've saved lots on not buying the Fluke (yet)<br />Also,slow,once engaged,will not disengage until you turn the ignition off,and back on.<br /><br />DHP

 

[angus63]

Re: Questions about a test tank?

You can use an eye dropper and place one small drop of water on each cyl on each head while it's running. If it boils away, you are too hot. If it steams and eventually disappears, you are borderline. If it sits there and stares back at you for a while, you are operating at normal temps. Just be sure to place only one drop on each so as not to thermally shock the head.<br />Good luck

 

[Solittle]

Re: Questions about a test tank?

-e - Unless you use a test prop you will need a tank the size of a swimming pool to run a 90 hp at 4200 rpm. Your motor will blow all the water out of a small tank in a heartbeat with the regular prop.<br /><br />I don't know the 2000 90s but all of the V4s I have seen have deflectors in the block to control water flow and if defective can cause a problem. You may also have an obstruction somewhere in a cooling passage. The V4s I have had should run in the neighborhood of 140-145 degrees. To check blockage you may need to drop the lower unit and back flush the system with a hose through your water pick-up tube (if you do that you may want to take the cover off of the t-stat housing). If that does not do it you may need to pull the heads & inspect the water passages - also the exhaust covers. <br /><br />If you are getting temp readings of over 200 degrees I would not (as you put it) "run it until the problem occurs."