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slickcrafthbc

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"Hello all,
I have twin 5.7&#

"Hello all,
I have twin 5.7's. One was replaced at 1000 hours befor I purchased the boat. The owner told me the other engine tested fine so it was not replaced.
These are both FWC engines on a 27' boat. My question; What is the best way for me to diagnose the health of my older engine (1988). Compression Test? What should the results be? How do I do it? No noticable problems to speak of but I thought I might try to get a sense of how tired the engine is. If I come accross a good deal on a new engine I want to know if it will be needed or not. As always thanks in advance"
 
"two indicators of engine heal

"two indicators of engine health are compression and oil pressure. If the rings or valves have had enough, compression will suffer. If main and rod bearings in the lower end are wearing out, your oil pressure will be below spec - especially at idle.

compression: use a compression tester. Plugs into the spark plug hole and you read psi after several revolutions of the engine using the starter (with all plugs removed). You should be looking for consistency in the readings among cylinders more than overall numbers... but that’s important too.

oil pressure: using a test gage, check warm and cold oil pressure at idle and at running speed and compare against specs.

A third benchmark to look for is consumption of fluids (oil).

Lastly - if you're maintaining it well and its running smooth and not consuming oil - leave it alone. The Chevy 350 is a time proven durable power plant."
 
"I would do a vacuum test, too

"I would do a vacuum test, too. That, along with compression and oil pressure will tell a lot.

For the compression test, set the throttle to WOT and remove the lanyard from the safety switch if it is injected or has an electric fuel pump. WOT will keep vacuum from drawing fuel into the cylinder with the gauge in it."
 
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