Volvo Penta 4.3GS Idle Rattle / Knock /// Water Tested ///

[bjcsc]

Greetings. I've been searching and reading here for a few days, but I haven't found anything to give me any direction. I have a 1998 VP 4.3GS that rattles terribly at idle - as if there were bolts knocking around in the intake. The spark plugs carbon up very quickly. When it warms up, it only does it from time to time. When the engine is under load it has no power. This boat was repowered with a new long block in the fall of 2004 (done by VP dealer). It was also fitted with a new carb (VP's version of the Holley 4160), intake and alternator. The exhaust risers and manifolds had just been renewed in the spring of 2004. It ran great for the 3 or 4 hours I was able to put on it before the year ended. 2005 was a very busy year for me (moved, worked out of town, etc.) and as such I did no boating. I didn't even start it. When I got it out this year, the anti siphon barb had broken off of the fitting at the tank and I had to replace it. It started right up, but was rattling. I assumed it was the fuel as even though treated, 18 months is a lot to ask. I have done the following, in the order listed, with no change in performance:<br />

• <br />
• Drained all old fuel, replaced with premium<br />
• Replaced Fuel Line to Tank<br />
• Replaced Fuel Filter<br />
• Rebuilt Carburetor (was very clean)<br />
• Replaced spark plugs<br />
• River tested, rattled till operating temp (~150) then barely noticable. No power-3000RPM no plane - white/gray smoky exhaust<br />
• Removed and cleaned plugs - dry carbon fouled<br />
• Checked compression - 145 on 2,4,6 and 143on 1,3,5<br />
• Checked timing at ~700RPM: 6'BTDC (to spec)<br />
• Test run on trailer - no change<br />
• Changed oil/filter (pressure was/is 40+PSi at idle)<br />
• Replaced ign. coil / checked cap/rotor/leads<br />
• Replaced plugs with 1 range hotter plugs / no change<br />
• Replaced ign. module<br />
• Cleaned spec heat range plugs and replaced the hotter<br />

<br /><br />I am at a loss as to what my next step might be and welcome any suggestions / opinions. Thanks.

 

[bruceb58]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Don't be offended by this next question. The reason I ask it is because I did it once. Took me awhile to figure it out.<br /><br />Any posibility that you have some plug wires crossed and you don't have the correct firing order anymore?<br /><br />Did you test the spark by pulling the high tension wire off the coil, inserting a screwdriver into the end and seeing if a spark would jump to ground(engine block)?<br /><br />Try pulling plug wires and replacing one at a time to see that each time you do this, you notice a drop in RPM.

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Hello. No offense taken. The order is correct, 165432. But I will recheck to make sure. Have not verifed spark as you described, nor tested by pulling wires. Will test as you described and report results. Thanks for posting.

 

[Mischief Managed]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Perhaps the rattle hgas nothing to do with the fuel delivery problem. Maybe it's mechanical in nature. Try running it with the drive belt(s) removed and see if the noise goes away. I thought minew had thrown a rod once but it was the water circulating pump that was making the loud knocking noises.

 

[Dunaruna]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Valve clearance, are these 4.3's adjustable?

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Originally posted by Mischief Managed:<br /> Perhaps the rattle hgas nothing to do with the fuel delivery problem. Maybe it's mechanical in nature. Try running it with the drive belt(s) removed and see if the noise goes away. I thought minew had thrown a rod once but it was the water circulating pump that was making the loud knocking noises.

Water pump was also replaced in Spring of 2004, but I will try it with the belt removed as you never know.<br /><br />Dunaruna: No, hydraulic lifters.

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Update:<br /> Checked plug wires. Order is correct.<br /> Checked HT wire for spark - good spark across a 1/4" gap<br /> Removed wires one at a time: same effect on engine<br /> Removed belt - same noise<br /> Checked fuel pressure (good)<br /><br />I also recorded a 10MB file of the engine running for those who may be interested. The sound reproduction is pretty accurate, although a little higher pitched than the actual sound(s). The video begins with startup and idle, at ~42 seconds we go to ~1200RPM, at ~1:20 back to idle, at~1:56 to 2000RPM and at 2:11 back to idle and shutdown. If you would like to view the video, click here . I appreciate all the responses.

 

[bruceb58]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Wow...that is not what I was expecting!<br /><br />Good idea to put that video on there.<br /><br />Does the sound appear to be coming from the rear of the engine at all? I am just wonderring if it's a worn coupler, bad drive alignment issue. I know that doesn't explain the power loss though.<br /><br />If it's not from the rear of the engine, I wonder if you have a valve train problem.

 

[Mischief Managed]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Well that is utterly perplexing (I watched the video). I haven't a clue what would cause that sort of noise in the engine. Any chance it's the U joints in the drive?

 

[Don S]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

I would say it's time to do some testing.<br />Vacuum test, compression test, maybe a leakdown test. <br />One of them may point to the problem.

 

[boathog]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

try running it without the drive.

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Thanks for the responses. It is no doubt a terrible sound. The drive was rebuilt in the spring of 2004 as one of the water seals was dripping. I had it rebuilt before it became more than a drip. PJX PowerJet = jet drive. There's not much to it (no U-joints, no gears, no transmission). It's a straight shaft from the drive coupler to the impeller with a few bearings and some seals. As such, I could fairly easily pull the shaft and run the engine alone. However, the noise, as stated in original post, seems to be coming from the intake area. I would think if it were a drive issue it would be more consistent and worse at higher RPM's, and would not be likely to be fouling out the plugs. (Then again, if what I think had been accurate I wouldn't be typing this.) I was thinking sticking valves but when I checked the compression - ?. If i had a valve issue, would it not show up in the compression test? My understanding of a leakdown test is to pinpoint a poor compression cylinder's problem (rings, intake v., exh. v.) I have not measured the manifold vacuum (or checked for vacuum leaks) so that is something I can check and report back on. Although again I would expect a lean condition and not carbon fouled plugs with a vacuum issue. Also keep in mind that this problem resulted from storage, and although it doesn't freeze here, the boat was properly winterized as a precautionary measure. I have done leakdown testing before, but what would be the best procedure to find each cylinder's TDC as the spark plug holes run pretty perpendicular to the cylinders? Are there any other tests I can run on the ignition system? What should the strobe pattern look like if I read the HT lead? Can I test the pickup coil?

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Update:<br /> Good news...checked manifold vacuum and it was lousy. ~13" at idle. It was steady at 13. Rises steady with engine RPM and interestingly enough around 1300RPM when it is at about 18 the noise is just noticable. If I accel to 1200RPM, the vacuum drops to ~7 and jumps to 16. When I decel back to idle, it jumps to 22 and then settles in at 13. I ran a propane torch around the intake manifold bolts and sealing edges as well as carb base with no noticable change in RPM. Ran out of daylight, but I will retest with starting fluid tomorrow. Assuming I find no external leaks, what's next? Seems to be looking like a timing issue...

 

[Don S]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

The link below ought to explain it.<br /><br /> http://users.bigpond.net.au/ergoff/vac1.htm

 

[Don S]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Was going to post this a little bit ago but forgot to add it to the vac gauge post.<br />Your compression test is also questionable to me. I seldom see any compression readings that are only 2 psi apart. Be sure you are using the correct method to check the compression. Otherwise your readings don't mean very much.<br />Here is a link to the Merc service bulletin put out by GM. The Volvo bulletin is almost word for word. But I have a link to the Merc one.<br /><br /> http://www.boatfix.com/merc/Bullet/97/97_25.pdf <br /><br />I would also replace the cap and rotor if over a couple of years old. They just don't last like automotive.

 

[bjcsc]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Don S.:<br /> I appreciate the help. I followed the procedure in my Volvo Workshop manual for the compression test. It is only slightly different than the bulletin you linked (thanks for that, too, because it also contains leakdown testing procedure). My manual says to crank through at least four strokes. I did 6 after warming engine up to temp and disconnecting the 2-wire grey wire at the coil (per the manual). The other difference in my procedure was that I only removed one plug at a time instead of all first as this was not clear in my manual as it is in the bulletin. I will redo the compression test tomorrow per the bulletin and post the results. Please check back. I have pictures of the vacuum gauge animations in my service manual but that's a great link. My best guesses are late valve or late ignition timing. What are yours? Will pick up new cap and rotor tomorrow morning per your suggestion.

 

[Don S]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

I've listened to your video another half a dozen times. Last few times with the sound turned up. It sounds like a spun bearing or possibly a piston siezing, which would explain the loss of power.<br />I would sure get a mechanics stethiscope and check to see where the loudest sound is coming from.

 

[lilmandavis]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

that sounds like a motor i had that dropped a valve... very interesting. id say its definitely not good to run her any more. id verify the sound is from the engine like don said with a scope. or find exactly where its comming from. and if its the motor id would almost certanly take the heads off just for personal satisfaction.! seems like if the timing was off that bad it would be backfireing. or die out.last time i heard that noise i took the heads off to find the valve head bouncing around. but, the valve stem was still in tact with the rocker??? looked normal untill i got the head off. http://i78.photobucket.com/albums/j91/joshuaj_33909/100_3035.jpg i would most surely take dons advice and scope it out real good!!

 

[newport dave]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

I have to agree with Don, it sounds pretty serious. I was thinking broken piston skirt. It could still have good cranking compression if that was the case.<br /><br />Dave

 

[bomar76]

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Re: Volvo Penta 4.3GS Idle Rattle / Knock /// FIXED! ///

Yank off the oil filter, carefully cut it open.....I'll bet you'll find it full of bad things,,,,,