compression on 94' 200 Johnson

[omceed]

The compression on my 94' 200 Ocean Runner is: cyl.#2-105 cyl.#1-105<br />cyl.#4-110 cyl.#3-109<br />cyl.#6-105 cyl.#5-108<br />How do these readings look for a motor of this age?<br />Also, what should the water pressure gauge be reading at 4,000 rpm?<br />This forum is great!<br />Thanks in advance for the feedback!

 

[walleyehed]

Re: compression on 94' 200 Johnson

I'm no guru on the V6's, but I'd say comp looks good overall....less than 10% difference, and it depends on the method of testing.<br />As far as water pressure goes, again, I'm not running V6's, but 20-25lbs should be close?? That question in particular might be better answered by a more knowledgable Tech.....

 

[Hooty]

Re: compression on 94' 200 Johnson

Walleyehed haz it right. Compression readings within 10% of each other. Max. water pressure 20psi plus or minus 2-3psi. Mine runs 18psi.<br /><br />c/6<br />Hooty

 

[Solittle]

Re: compression on 94' 200 Johnson

Water pressure will depend somewhat on the distance that the guage is from the motor.

 

[Hooty]

Re: compression on 94' 200 Johnson

In real life, it doesn't make much difference how far the gauge is from the engine since there is no flow to it, only pressure.<br /><br />c/6<br />Hooty

 

[Solittle]

Re: compression on 94' 200 Johnson

Hooty - It did on my boat. I had mine originally mounted near the transom. I moved them to the CC and there was a significant difference.

 

[Hooty]

Re: compression on 94' 200 Johnson

If all you did was move the gauge farther away and the reading went down, you've either got a leak or the gauge went nuts.<br /><br />c/6<br />Hooty

 

[omceed]

Re: compression on 94' 200 Johnson

Thanks to all for the feedback.<br />Today at WOT(5500rpm '94 OceanRunner 200hp,@ 49mph) I was at about 15psi.The gauge is at the helm.<br />At idle though it only shows about 3-4lbs.I understand that OMC's of this vintage are high volume lower water pressure motors.<br />Waddauthink?

 

[seahorse5]

Re: compression on 94' 200 Johnson

Those big blocks of '93 and later used a higher pressure cooling system and required a 60 psi pressure gauge. Most correctly set up motors will run in the 25 and up psi range at high speeds. Where is your water pressure fitting? It should be on the base of the adapter plate, below the powerhead. Make sure that your "blowoff" valve is not stuck, and it would be a good idea to replace the plastic valve tip with the '97 or later version that has air bleed grooves in it.

 

[Selles]

Re: compression on 94' 200 Johnson

what is the name of the instrument that you use to measure water pressure of outboard

 

[seahorse5]

Re: compression on 94' 200 Johnson

At idle, the big OMC's will only show a few pounds of pressure (between 2 and 10) on a dash mounted water pressure gauge.<br /><br />The most common cause of low water pressure in the '93 and later big block motors is the wrong water pump kit installed. The 5001595 kit is the one required on ALL Johnsons and Evinrudes with the "split-line" gearcase.<br /><br />All others with gearcases without replaceable plastic water inlet covers, use the 5001594 kit that looks almost identical, but the housing has a bleed hole near the stb. aft end. <br /><br />When ordering water pumps or other lower unit parts, make sure to use the complete model number and use the correct parts book page.

 

[omceed]

Re: compression on 94' 200 Johnson

Thanks Seahorse!I will lookn and see where my water pressure fitting is.How will I know if the blowoff valve is stuck? Is the new kit something that is easy to install? I did a regulator/rectifier, I guess it should be easier than that.<br />Great info and I will get back with ya.

 

[seahorse5]

Re: compression on 94' 200 Johnson

The blow off valve is just below the reg/rectifier on the aft part of the block. You will recognize it by the 2 hoses coming off the plastic housing. Remove it and replace the valve and the seal. IT is spring loaded so use care and make sure the seal is facing the correct way.<br /><br />Your water pressure pickup should be in the adapter plate below the powehead.

 

[omceed]

Re: compression on 94' 200 Johnson

Thanks Seahorse, I will get the parts and get back to ya after I do the job.