V6 3.0L with bad pronostics.

[dompie99]

Good day Y'all, I've been out of this site for a while due to me parting with my good oll 2.0 175 mariner. It ran very very well till i sold it two years ago. :reddevil: now here is the new story. I bought yesterday an Hydrostream HST pretty well equiped, it has a 3.0L carbed V6 225hp, hot-foot, power lift (defective), Lower pick-up (aftermakket done, he should have kept his daytime job) with all gauges working electricity and the trailer (single axle) as well for 3000$ CDA. Now here is where it get's complicated, i swore BEFORE going to get the boat that i will check the compression BUT i didn't since the guy lowered the price from 5900 to 3000 after a rough discussion and I left with the rig. It starts well, run on idle okay, (just did a little dip, it was 1;00am and seemed to run equal. Today, when i came back from work, i checked the compression AND, ohhh so sad, they are ALL at 50 PSI WOT on starter after 4 of 5 pop on top. That's the sad part. There is STILL this VRO oil pump attached to it ( I will remove it ASAP) before it blows the rest of it and destroy the block. I will go and get a small camera to inspect the cylinders from the plug hole to see if there is scars mack or major malfonctions within the engine although I will find out soon enough. The hull is in good shape considering that it's 1990, no dents, break or things to bring worry at all, i went inside and from what i could tell, it is rock solid. no weird braces, or broken elements of Transom cracks at all (no repair evidence either). I do remember that there was a guy up north New-York State (neas Saratoga i believe) that had quite a few bare blocks 2.4, 2.5 or 3.0L engine and i was wondering if he would be still in this site . I know that i will have to pull out the upper unit and re-do it all (pistons ring and rebore) for it to be running great next year. Is there some thing that I should be checking besides these pistons/rings/reed plate, and gasket set that I should be inspecting more closely ?? And also, the serial number is 0G052638

[south599]

You do the check with the motor warmed up, all the spark plugs out, and the carbs pinned open.

[CharlieB53]

Most motors will not even start with compression in the 50's.

I suspect you have a problem with your tool, retest using a different compression tester.

Edit: Slow cranking speed can lower #'s. Make sure battery charged, all cable connections clean, bright, and tight. Starter brushes and comm clean, etc..

[petehubbell]

Like the other posters said! Get another compression gauge.......PH

[dompie99]

Good day , when the tests were ran, i pinned the carbs WOT and all spark plugs were removed but the engine was cold. According to the hour meter, (if it was not disconnected at some point and time) reads 458 hours. I will get another Compression gauge this very day and get back to you ASAP.

[dompie99]

Ohhh by the way, How ''fast'' could I be expecting this rig to ''fly'' on water pretending that the engine has no major bugs. ??

[Capt.Insane-o]

It should run into the high 80's or more unless it's heavy.

[dompie99]

Okay, i went to Mercury site in order to find out more about this new (old) rig and I found out that it is a 1994, (3.0L V6 I already knew) engine. That it has only 458 hours on the hourmeter..... and it was maintained at Polesono in Coteau du Lac in Qc. I will give these guys a call in order to have more détails as to the crunches of the maintenance done to it ( rebore, rebuilt etc etc )

[dompie99]

Update. I bought another compression gauge and, you guys were right, the comp on 5 cyl. is 110 PSI cold, on of them (bottom left bank) is 90 psi.....i looked with a camera inside the cylinder and there is one little scar...it's sad and also, want to correct the hours meter, it is 348 hours..... again, i don't know if the hour meter was ON every time the engine was fired but it sounds about right...