yanmar 315 lack of mid range power

scarab racing · 31-03-2009, 10:40 AM

From tickover to about 1900-2000rpm pick up is realy good then it just hovers until the rev's build realy slowly till the turbo kicks in, then acceleration and power is great its just the 1900 - 2200 rev range that is dead.
Any surgestions or adjustments that you would recomend we try?

Also "seems" to have more power if we back of from WOT when trying to accelerate i.e pulls on to the plane quicker if only given half to three quater throttel. any help most appreciated.

I know these engines are known for taking time to spin up but the bottem power seems realy great then everything just stops, until the turbo cuts in.

TECKNO 40 · 31-03-2009, 10:59 PM

How many hours has it run?

scarab racing · 01-04-2009, 08:17 AM

Hi Tenko
About 250 hours total, 25 hours since rebuild i.e head off,valves ground and reseated, new crankshaft. Initial puff of grey smoke on start (from cold) and very small puff of black when accelerating from tick over but very very small puff of black. Great starter hot or cold, tick over is smooth and quite. What are you thinking it might be?
Regards

TECKNO 40 · 01-04-2009, 09:36 PM

We have had a few problems with the injectors being set to low they perform ok when tested but you need to make sure they are set to the highest end of the range think that is 260bar.

scarab racing · 02-04-2009, 08:35 AM

Hi Tenko
Thank you for that will check and get back to you.
Have you tryed any tunning on these engines ie even higher pump preasure or turbo adjustments, uping the rev limiter?.
I want to get it running right first but didn't know if youve tryed anything?

scarab racing · 02-04-2009, 08:36 AM

Hi Teckno 40
Sorry about name spelling in last post

chris · 02-04-2009, 08:22 PM

out of interest where did you get the yanmar from i used to have one in an extreme , great engines but that was always the problem slow untill the turbo then wheeeeeee,mine used to be even worse in hot weather,my friend had same set up as me except he had a bravo 3 that med it much better on acceleration

scarab racing · 02-04-2009, 09:37 PM

Hi
I've had the yanmar for a few years, I agree with it being dead until the turbo kicks in but it pulls well at bottem end then goes dead until all hell breaks out when the turbo spins up.
regards

TECKNO 40 · 03-04-2009, 10:38 PM

Why was it rebuilt after 225hrs?

scarab racing · 05-04-2009, 07:49 PM

Hi
Reason for rebuild was it valve bounced and bent an inlet valve and snaped a rocker so whilst engine was out the boat it seemed sensible to strip down and check every thing.

Jon Fuller · 05-04-2009, 08:06 PM

Valve bounce! How did you manage to over rev a diesel? change down too many gears?

TECKNO 40 · 05-04-2009, 09:06 PM

The warrenty on it is 5 years at 225hrs it should be younger than that !

scarab racing · 05-04-2009, 11:15 PM

I only changed down a couple of gears as it was a big hill !!!! but did get some good air of the top of it.
Dont no the exact age of the engine but do know that it showed about 200+ on the hour meter before I purchased it.