Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

[costerbi]

I have a 1997 Four Winns 170 Freedom with a 3.0l volvo penta 4 cylinder. I have only had the boat for ~2 months and when I first took it out I noticed a terrible vibration at idle and varying temperature when running around 3500rpm. I took the boat to a shop and they determined that I had a cracked manifold and it was leaking water into the exhaust and when it would fill with water it would cause the 4th cylinder to miss giving me the vibration at idle and when opening the throttle the water would clear the exhaust and no miss or vibration. Well, I had that shop replace the exhaust/intake manifold. I took the boat back out and it had a less intense vibration when putting it in gear with the engine at idle but it was still vibrating/missing at idle. I took it back to the same shop and they told me that the carb was very dirty and needed to be cleaned/rebuilt. I let them rebuild the carb and drain the fuel tank so that I could put fresh gas in it.

Even after all that the boat still had a rough idle, however, when I adjust the throttle just above idle it smooths out. Also, I have no hesitations or problems running at WOT or cruise speed. When I have the boat on muffs or in neutral it seems to run fairly smooth but when it is in the water and in gear it is very rough until I give it some throttle ~1000rpm, the idle speed is set to ~800rpm. I have since replaced the distributor cap, rotor, spark plugs, and spark plug wires with no change. I have also used Sea Foam fuel/carb treatment down the carb and in the fuel tank with no change. I have checked and verified that all the cylinders have good compression. I did notice that #3 & #4 spark plugs are black in color while the #1 & #2 spark plugs seem to be burning fairly clean and the ceramic of the plugs are still white. Not sure what that means? I have also attempted to adjust the idle mixture screws which does have and effect on the roughness of the idle but I am only able to make it worse and not better with those screws. One screw is ~3 turns out and the other is ~1 turn out, should they be the same?

Does the issue I am describing correlate with any possibilities of the shop making a mistake when rebuilding the carb? The shop ended up telling me that the 3.0 penta's generally run a little rough and there was nothing they could do except recommend me run clean gas through it for a while and maybe it would improve but I know the "idle-in-gear" is not normal. It shakes/vibrates the whole boat. Oh, I have also installed a new prop to rule that out.

Any advice would be greatly appreciated!

 

[Don S]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

2 things to check. Make sure the timeing is perfect to prevent head gasket loss. (if you have EST dist. you will need a shunt to put it in base timeing to set it.)
Then make sure the idle mixture is set rich enough. A lean mixture on the 3.0L engines wil make them hard to start, idle rough, and diesel when trying to shut it off.

 

[sabastianunf]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

Have you checked the timing?

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

It sounds like I need to check the timing which is something that has not been done. I will check that tomorrow afternoon and get back to you as soon as I do that.

The boat is very easy to re-start and takes off, cruises, and runs at WOT just fine (there is no pinging). But, manuevering in the marina is scary and embarrasing.

Just two questions related to checking the timing, how do I know if I have the EST ignition and if I do where do I put the shunt?

Thank you very much for the help so far

 

[Don S]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

The first thing you need to do is to determine what year ENGINE you have. While your boat may be a 97, the engine package could be older, or newer.
You need to find the serial number or FULL model number of the engine to know for sure.
This should help. Volvo Engine ID
Since it's about mid of those models, it's a gray engine and it does have the Delco EST distributo.
I will post some info for setting the timing after you post what model or SN you actually have.

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

My model number = 302CPLKD
My serial number = T01303314

Do those numbers help?

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

Also, the motor has a tag with spark plug and spark plug gap information but for timing is says, "see service manual" instead of telling me the timing spec.

 

[Don S]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

Also, the motor has a tag with spark plug and spark plug gap information but for timing is says, "see service manual" instead of telling me the timing spec.

That is because it isn't just hook up the timing light, aim and read. There is a process to put it into base timing mode so you can check the timing and adjust as necessary.
Even if you found the specs and tried to adjust the timing without putting into base timing, even if you could keep it running it wouldn't run very well.

PS, it's an LK model and I will post some info shortly.

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

I do very much appreciate the time that you are spending on this.

 

[Don S]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

Here is what the manual says for setting your timing.

Setting Timing
The timing procedure for Delco EST system requires shunting (shutting
off) the electronic spark advance. Follow the steps that apply to
your specific model.
2 1. Install Timing Test Lead, Volvo Penta P/N 885163-6 A , into
distributor and connect bare lead to a 12-volt engine B+ source. Start
engine.
2. Direct beam of timing light onto timing grid. Loosen distributor clamp,
then turn distributor slowly by hand until timing mark is set at the appropriate
timing figure. See Tune-up Specifications in the General Information
section of the Engine Service Manual.
3. Recheck timing mark; reset if necessary. Tighten clamp bolt.
4. Stop engine. Remove adaptor plug.

Your engine should be at 0? TDC with the shunt installed.
You can order the shunt that plugs into the distributor from your local VP dealer.

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

do you know what the idle rpm should be when looking for 0 degrees TDC.

 

[Don S]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

It doesn't mnatter as long as it's somewhere aroung idle. Being in base timing means it won't move no matter what the rpm.
What you REALLY REALLY need to do if you want to work on your engine, is to get the OEM manuals for your engine.
With the SN and model numbers you gave, your engine and drive are OMC. However, they were during the OMC/Volvo Penta joint venture and the Volvo manuals are readily available. The come in different sections you need the following.

Engine Components..... 7797361
Electrical and Ignition..... 7797362
Fuel Systems..... 7797363
Also a drive manual for whichever drive you have.

 

[bjcsc]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

I'll only add 2 things:

1) When you are finished setting the timing, with the shunt removed, you can check to see that your ignition module is doing it's job. (This is especially easy with a good advance timing light that reads RPM). This is what you should see:

RPM Advance
600 10?
1500 17?

2) A lean condition can also be caused by a vacuum leak. Considering the work you had done, it might be a good idea to check that you do not have an intake manifold / carb base /other leak.

Good luck!

 

[costerbi]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

The shop that worked on my boat also removed the thermostat because they said the thermostat housing was too corroded to re-install the thermostat unless I bought another housing. My temperature gauge doesn't even move on the dash, could this cause my idle problem? The timing was a little advanced but not too much and didn't seem to correct the problem. Any other suggestions?

Thanks,

 

[Limited-Time]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

In order for the cooling system to operate correctly, and hold the engine at the correct operation temp. the thermostat must be installed.

 

[Coors]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

You need to find a new shop.

 

[dollarart]

Re: Volvo Penta 3.0GS Rough Idle, Smooth Accel? Help?

Don S,

What is a "B+" source ?? Can I just connect the + lead to the battery ot the batt cable at the starter ???

Another question...my 2003 3.0 has 5 nothes on the timing "plate"...do I assume that the center notch is 0 degrees ??? I do realize my motor gets set at 2 degrees ATDC...just not sure which notch that is.