165 hp mercruiser help

[yoda132]

Hello all, i'm a new boat owner also new to the forums.

We bought a 1975 sea ray srv 193 with a 165hp inline chevy 6 cylinder. The motor runs pretty good and we have had her out on the water 6 times. This morning before going out i checked all the spark plugs to make sure they were in good shape.cleaned and reinstalled. i removed the flame arester and when i pulled the hose off the rocker cover from the flame arester i found a pasty whitish looking substance in the hose. I looked into the top of the valve cover and its all sludgy in there also. I pulled the dipstick to check for water in the oil and the oil looks fine? what can it be? head gasket? any help would be apreciated. thanks:facepalm:

 

[Bondo]

Re: 165 hp mercruiser help

what can it be?

Ayuh,... Welcome Aboard,... Probably condensation,...

Don't worry about it, go Boatin'...
At the end of a day, it'll be Gone, evaporated away..

 

[yoda132]

Re: 165 hp mercruiser help

I hope thats all it is, its not thin it almost looked like someone put pudding into the top end. if it help's i will take a picture of what i'm seeing and post it. but it will have to wait till tommorow as its to dark now.

 

[yoda132]

Re: 165 hp mercruiser help

I took the boat out again, one thing i noticed is i have 15 lbs of vacuum at idle when i open it up it drops to 0,still seams to run ok. after having her out when i got home i checked the top end again and still have vanilla pudding inside the rocker cover and when i pulled the dipstick had a small amount of white on the stick. so any suggestions? intake gasket? head gasket? I just wanna get it right so i don't have any worries. thanks for any input.

 

[Ancloter]

Re: 165 hp mercruiser help

The 'vanilla pudding' is water mixed with oil. A small amount is common for an I/O due to condensation. It's unusual/unacceptable to have it on the dipstick after running since it should have evaporated. The low vacuum is a clue of an underlying issue, probably gaskets.

I'd do compression test to check for a bad head gasket. The drop in vacuum at higher rpm would seem to indicate a head gasket. I'd also replace the gasket on the valve cover and re-torque the intake and exhaust manifold bolts. I'd start by re-torqing the head gasket. Make sure to use a torque wrench. I used to back mine off then reset them in the proper sequence to a bit more than the specified torque. I think for those engines they use the 'swirl pattern'. Loosen from outside in and tighten from inside out.

Also pull the plugs and inspect them. Are any of them clean or have water on them, particularly #5 or #6? That would indicate a blown elbow riser gasket which must be replaced.


These are good engines btw. They're also a power option for the Chevy C-10 pickup in those years. I used the same Chilton's manual to rebuild my C-10's V-8 350 as I did to rebuild a 165 (GM I6 250) in my boat.

 

[yoda132]

Re: 165 hp mercruiser help

thanks for the reply, i'm just gonna buy the upper gasket set and redo all of them,i will do a compression test before and after.

 

[79Glastron]

Re: 165 hp mercruiser help

I'm not sure I would be taking that engine apart yet. If the engine idles well I wouldn't worry about the vaccum reading. Seeing 0 in/hg at open throttle is normal. Check compression if you want. Report back

 

[dubs283]

Re: 165 hp mercruiser help

The drop in vacuum at higher rpm would seem to indicate a head gasket

no...a drop in vacuum at higher rpms is normal

but yes, do a compression test - this will give you a starting point for troubleshooting

 

[Fordiesel69]

Re: 165 hp mercruiser help

Do not buy gaskets to throw at it. Mostly likely a riser gasket, or cracked manifold (common).

Previous owners do not winterize correctly, or the manifold just cracks from age and rot.

 

[yoda132]

Re: 165 hp mercruiser help

I talked to the previous owner tonight, he told me last fall the boat was left in the water at his friends house and partially sank. this would have been nice to know before the purchase. He said he changed the oil when he winterized it but i'm leaning on not. this could be where the water came from.

The boat runs pretty decent and does not overheat at all,last i had her out we ran it around the lake for about 1/2 hour straight and the temp never climbed above normal.

Thanks for letting me know about the vacuum. My first line of attack is going to be an oil and filter change,new plugs,ect and a compression test. i will post up what i find. thanks for the help guys i appreciate it.

 

[yoda132]

Re: 165 hp mercruiser help

btw how can i get the pudding out of the top end so i can tell if i'm getting more water?

 

[Ancloter]

Re: 165 hp mercruiser help

Since you apparently have a vacuum guage you should start there. They're more usefull than a compression test and will do that too.

The vacuum should only briefly drop to 0 on rapid acceleration with a '75 Merc 165. During deceleration it will do the opposite and go way up. It's due to the throttle plate. At sustained higher RPMs vacuum should be steady and between 15 - 20psi.

Having 0 vacuum at sustained higher RPMs is a sign of bad oil or worn rings.

 

[Ancloter]

Re: 165 hp mercruiser help

Re: vacuum. I figured you'd be checking vacuum out of the water on the muffs. If you check vacuum in the water it will have lower vacuum at high RPM due to the water's back-pressure on the exhaust. Best to check it on the muffs.

 

[yoda132]

Re: 165 hp mercruiser help

ok i will check vacuum after i get the oil changed and run it on the muffs i will report back my findings.

 

[dubs283]

Re: 165 hp mercruiser help

don't worry about the vacuum - the guage you have probably isn't even numerically accurate

just watch for the vacuum to be lower at higher rpms, e.g. high vacuum at idle, lower vacuum at cruising speed

besides you got the answer to your water in oil issue - previous owner didn't tell you the boat sank

as long as the engine runs fine, you are okay