twin inboard engines

antlr-king · Post by **antlr-king** » Mon Jul 04, 2011 5:49 pm

just a quick verification. a trojan express 30 with twin 318's. which one of the engines is the counter rotating one?

prowlersfish · Post by **prowlersfish** » Mon Jul 04, 2011 6:20 pm

Starboard ( right ) side in most cases ( seen them pulled out and put in wrong ).

antlr-king · Post by **antlr-king** » Mon Jul 04, 2011 7:02 pm

thanks that is what i thought. when there running they turn away from each other. facing the engines the starboard one turn counter clock wise. thanks.
also was wondering what that compression should be on these engines. i did a compression check on both this weekend and they were all over the place. from 45 to 105.?.
what is normal?

Big D · Post by **Big D** » Mon Jul 04, 2011 8:47 pm

Ditto Paul. When determining the engine rotation in a marine application, you get behind the engine and face the flywheel. Left hand spinning flywheel is standard engine rotation. In a V-drive configuration, the front of the engine will face the back of the boat so that changes things. If it is a straight out shaft with no v-drive, as Paul said; counter rotator is on strb side. When behind the boat looking at the props, in a standard prop rotation configuration, the strb prop rotates clockwise and port counterclockwise. OK, I'm confused now!!

Compression should be 120-150 but anything over 100 and consistent for the age is good. 45 is too low. Having said that, a leak-down test would tell you if it's upper or lower end. If upper, not bad; could be just heads, valves, gasket, if lower; you're pulling the engine.

prowlersfish · Post by **prowlersfish** » Mon Jul 04, 2011 9:06 pm

45 ? not good , run it at recheck it . do the cylinders that read low first , so they won;t be washed down and the battery is up. Make sure you use a screw in gage . The ones you hold in leak like crazy .

Big D · Post by **Big D** » Mon Jul 04, 2011 9:30 pm

Good points Paul.

jddens · Post by **jddens** » Tue Jul 05, 2011 10:15 am

Make sure to warm the engine prior to the compression test. I did a cold test and thought I had a bad engine, 85-120 readings..........did it again warm and it was 150-160 all the way around. No problem.............

antlr-king · Post by **antlr-king** » Tue Jul 05, 2011 6:44 pm

i did run the engines for about 10 minutes before the check. the ones that checked 80 and below we squirted with oil then rechecked. those came up but none of them checked as high as you say is good. 120 to 150. only 2 went to around 105. right now im thinking repower. should i go back with 318's? im thinking 350's since i hear they're more fuel efficient with more horse power. what do you think? would i have to change a whole lot? or would they fit where the 318's are?

prowlersfish · Post by **prowlersfish** » Tue Jul 05, 2011 7:14 pm

How do they run ? , I would invest in a new compression gage screw in type, I find it hard to believe the readings all are low .

To get a good reading you must have a good cranking speed ,Low cranking speed can cause low readings , open the throttle a closed throttle can cause low readings too .

antlr-king · Post by **antlr-king** » Tue Jul 05, 2011 9:22 pm

we had the screw in gauge. the trottle was wide open. now i dont think the turn over speed was as fast as it should of been. also have alot of oil leaking from one of the oil filter mounts. not the threads or the filter itself. also a small hole or gasket leak around the intake manifold both on the starboard engine. they seemed to run ok. also the starboard engine has blk smoke coming from exaust at around 2400 rpm. low oil pressure and engine temp guage reads low. but the red light on the fly bridge came on. i assume that meens over heat. then i noticed a small water leak under the head on the left side at the rear of the head.