Volvo Penta AQ170C Straight-6 Valve Clearances Question :)

[boatingmark]

Hello all,

Its been a fair while since I've been on here let alone posted a question :/ , my boats taken a bit of a back seat due to a house renovation.

However, I'm spending some time this coming weekend sorting the boat ready for the season ahead!

I checked the valve clearances last year before laying up and they are miles out so its the first job!

Please could anyone point me in the right direction with information on the order in which to set them and the correct clearances for this engine.
This will be the first time I've ever adjusted valves so any info will be greatly appreciated!!

Thanks in advance chaps

 

[Scott Danforth]

its in the manual. you can look up the manual on this site Boatinfo - boat brochures and manuals for boats and marine engines!

 

[boatingmark]

Thanks Scott!

I have followed the manual but struggling a little, I'm hoping someone could please help me

It says to adjust valves 1,2,3,6,7,10 when piston one is top dead centre, then,
4,5,8,9,11,12 when piston 6 is top dead centre.

When i got piston one top dead centre it brought piston 6 top dead centre also, i understand they run in pairs but is this right? I wonder why the manual is worded like this if I'm to adjust all valves at once without the need to turn the engine again.

My other issue is i have turned the valve adjustment screws as far out as possible on valves 4 and 5 but the push rods are tight upwards against the tapets meaning there is no adjustment.
These 2 rods do visually look higher than the rest as well. I cant make sense of it and now worried i have damage somewhere?

What am i doing wrong? Anyone? :/

 

[Scott Danforth]

follow the manual. you can only do the valves as the manual calls. has to do with the fact that there are 6 pistons and the crank is bent so they dont all go up and down at once.

regarding valves 4 and 5, you are adjusting with piston #6 at TDC, correct? if not the cam is trying to open the valve. hence the reason to follow the manual.

 

[boatingmark]

Thanks Scott, yes, both No 1 and No 6 pistons are at top dead at the same time yet the rods on valves 4 and 5 are higher than the rest and i have backed the adjustment screws right out to the point there is no adjustment left and the rods are touching the tappets. :/
I've followed the manual but seem to have this problem and struggling to work out what to do next!

 

[wklose]

The instructions are referring to adjusting a group of valves while #1 cylinder is at TDC on the compression stroke. This will put #6 at TDC on the exhaust stroke . Then rotate the engine until #6 is at TDC on the compression stroke and adjust the next set of valves. That is why some valves appear to have no adjustment , the lifters are up on the cam and the valve should be open.

 

[boatingmark]

Thanks for that, its making sense now. ( a little knowledge is dangerous huh! )

So, once i have adjusted the first lot of valves with piston 1 at TDC on the compression stroke i would need to turn the engine 360 degrees for piston 6 to be on the TDC on the compression stroke then adjust the next lot of valves!?

Please can someone also confirm i am looking at the engine the right way with the flywheel being the rear of the engine and the crank pulley the front!?

 

[wklose]

Yes , After adjusting the first group, rotate the engine 360 degrees and do the second group. #1 should be the front most cylinder, closest to thew crank pulleys.