Volvo Penta GiIB 2001 Gas Engine Knocks and low power and overheat no WOT

"Symptoms:

- Engine will no

"Symptoms:

- Engine will not exceed 3600 rpm under load
- Engine beeps intermittently with overheat alarm but quickly cools off once RPMs are dropped to 1900
- Engine clacks on top rhythmically consistent with RPM after 1500 rpm (and higher) is reached (but not under 1500 rpm).
- Engine clacks whether under load (in gear) or not.
- No water or radiator fluid in oil
- No bubbling in radiator reservoir

Measures taken thus far

- Impeller new and clear
- Radiator hoses new and clear
- Radiator fluid proper 50/50 mix and not leaking, cap verified as not leaking.
- Heat exchanger inspected and verified clear of crap, impeller blades, etc.
- Fresh water flow very good
- Exhaust Manifolds removed and inspected (clear).
- Plug wires and spark coils have been swapped with my known good engine to troubleshoot integrity of those components.
- Oil and oil filter just changed to 20w50 synthetic.
- Injectors for suspect cylinders 4 and 6 have been pulled and swapped with known good cylinders. The problem stayed with the bad cylinders (did not follow the injectors).
- Removed valve cover and inspected rockers for any play. I could not move any of them. Everything looked very clean. No bent rods or valves noticed (but I did not remove the head).
- All cylinders and plugs are hot after engine runs (even 4 and 6)

Planned tests/maintenance

- Compression test has not been run. I am borrowing a tool tomorrow to run the test.
- Seafoam in oil and air intake.

Other notes

- This engine is a closed cooling system with a heat exchanger.
- 375hp Volvo Penta, 2001, 8.1 GiI-B, serial 4012064207, gasoline
- I have a MEFI4 electronic analyzer and I ran a balance test, disabling cylinders one at a time while running at 1500 rpm. When I disabled cylinders 4 and 6, the engine rpms did not change noticeably. Disabling all other cylinders individually caused the engine rpms to dip noticeably.

I hope I included everything but I'm sure there will be questions. Any ideas? Can we narrow this down to just a few components. I'm thinking head gasket."

Any DTC codes? How is the OP

Any DTC codes? How is the OP and temp?

Head gasket would give the symptoms you describe but would also be leaking coolant into the cylinders. This would show up on the plugs and you would be loosing coolant from your reservoir.

The alarm you hear may be the knock sensor engaging. That's why it is critical to know the DTC history.

It could be as simple as a crank sensor or MAP sensor but the compression test will be very helpful.

"When my MEFI analyzer arrived

"When my MEFI analyzer arrived, it had 2 codes: -Low Oil Pressure and Overheat. I reset those codes and need to run the engine until the alarm sounds again to see if the same codes come on.

-The low oil pressure is surprising since the oil level has never been below the marks on the dipstick.

-There was no knock sensor warning.

-The only other thing that I have noticed at idle is that the spark advance settles around 2-3 degrees instead of the published 10 degrees in the manual, but I know nothing of advance."

"If the engine overheated it i

"If the engine overheated it is very possible the oil pressure would have been low due to the additional temp. There is no DTC for knock retard but the engine history will show how many times and for how long the engine ran in the knock retard condition.

The timing at idle is not important as long as the engine idles OK and since your timing is not adjustable I wouldn't be concerned with it. I would, however, check the timing at WOT. This reading is important (around 36 if I recall). If the engine is not achieving full advance, there is an issue."

"Just completed the compressio

"Just completed the compression test. Ugly on Cylinder 4 and concern on cylinders 5,6 and 1. Also, the number 4 spark plug has some ugly deposits (this plug is only about 5 hours old!). I've included pictures and welcome your input regarding the type of deposit left on the plug. I also welcome any suggestions as to next steps...

Compression Test Results:
1 126
2 167
3 163
4 53 (yikes)
5 115
6 125
7 140
8 142

Picture 1"">
Picture 2"">
Picture 3

"Together with you compression

"Together with you compression readings and

"Engine clacks on top rhythmically consistent with RPM .... "

I'd consider the possibility of bad hydraulic lifters.

Also... did the engine ever run properly for you?
IFSO, when did the problem start?

"

"As I look back on it, I do no

"As I look back on it, I do not believe that this engine has ever run properly (I bought the boat used). I don't think I've ever seen it over 3700 rpms at WOT, and it's rated for 4600 at WOT. I have some updated compression numbers:

1 130 (4psi higher than prev test)
2 167
3 163
4 53
5 123 (7psi higher than prev test)
6 125
7 140
8 142"

"Robert,

You mention the po

"Robert,

You mention the possibilities of bad lifters. I inspected the length of every lifter (without removing the head). They do not appear bent. What else could be wrong with the lifter? All rocker arms look good. I was unable to view the valve without the head removed so I can see how might be a valve. Thanks for your input."

"Lets get some nomenclature st

"Lets get some nomenclature straight...
The engine turns the cam
The cam pushes on the lifters (which use hydraulic pressure for operation)
The lifters push on the push rods (which is what you measured)
The push rods push on the rocker arms
The rocker arms push on the valves.

The only way to "see" the lifters is to remove the rocker arm, then remove the push rod, then use a magnet to remove the lifter."

"Ahhhhh,

So the lifter is n

"Ahhhhh,

So the lifter is not the rod. I thought the lifter was the rod as well. Very interesting! I'm going to go look at some parts diagrams. Thanks!

What exactly goes wrong with lifters? Do they have excessive wear? Are there bearings involved? Just curious."

"Is the lifter sometimes calle

"Is the lifter sometimes called the tappet? Part 27?

that be it...

that be it...

"OK,

So if I follow the lif

"OK,

So if I follow the lifter/tappet theory, the flow goes like this:

1. Lifter is damaged on the exhaust side most likely.
2. When lifter was damaged, it created a situation where exhaust gasses could not be pushed out of the combustion chamber (because the exhaust valve could not open fully or possibly not at all) so the only place for them to go was through the head gasket (into the radiator) and/or possibly past the cylinder seals (into the oil).
3. This implies possible damage to the head gasket and cylinder seals of #4.

Am I on the right track here? Going to do some pretty major tear down tomorrow and would love to see some of you guys place odds on the various failed components before I return with pics of the carnage."

"RE: "only place for them

"RE: "only place for them to go was through the head gasket (into the radiator) and/or possibly past the cylinder seals (into the oil). "

No, since you said...

RE: "- No water or radiator fluid in oil
- No bubbling in radiator reservoir"

Blown head gaskets usually result in fluid in oil or radiator issues.

Tappet check does not require a major teardown.

Check the easy to do/fix stuff first...

Per your scenario.... incomplete exhaust gas scavanging will result in poor incoming fuel/air mixture on next cycle.

Also... tappet falure is no more likely on the exhaust as on the intake. My guess, is the intake as this is a FI engine and I would expect a rich mixture if the cylinder is getting most or if not all of its full load of fuel but not enough air... and your plugs look like they are running rich... unless that's oil on the plugs."

"OK,

So is it possible for

"OK,

So is it possible for me to get the lifter/tappet out with just the valve cover off? I guess I need to remove the rocker, lift the rod out and then use a magnet to recover the tappet/lifter?

When I remove the rocker, I assume it is important for me to accurately mark the position of that nut correct?"

"Rick,

Looking at my #4 plu

"Rick,

Looking at my #4 plug above, does that look like radiator fluid deposits? I really can't tell. I did notice that the reservoir is low and I know that I had it almost full the other day. I'm beginning to suspect a leak at the head gasket possibly in addition to the riser/tappet.

I tried to pull the head today, but I think it's out of my league. Just attempting to loosen the first bolt was pretty challenging."

That is the procedure..
Nut &

That is the procedure..
Nut ( #22 in diagram) is reinstalled and torqued to a specified torque value.

You might try pressure testing the cooling system. It's a simple test... tester available in any auto parts store.

"I pulled the nut out and pull

"I pulled the nut out and pulled the rod out and I could see the lifter, but it appears to be fastened in place. Does it just lift out or is it secured by something?"

"You can't take the lifter

"You can't take the lifter out without the head being off. I have the same engine just had to replace it because I lost two pistons due to mysterious cause, I do have allot of spare parts off my old engine if you find out you need anything let me know. Stuff like cam sensor crank sensor etc. You can't reuse the head bolts on that engine they have to be new."

"You might get lucky and only

"You might get lucky and only have a bad valve but it sounds like you lost a piston, probably due to a leaking head gasket. The rattle you hear is most likely the wrist pin. When water or coolant gets into the cylinder and sits a bit the wrist pin gets rusted. Once the engine is restarted the rust cuts away at the pin bore.

By the way you can remove a lifter without pulling the head, although you do have to remove the intake manifold, then the lifter retainer but why bother, the head has to come off anyway. A bad lifter will not cause low compression, a bent or burnt valve will. Either way, the head has to come off to make the repair.

This is not difficult with a little guidance. The rockers are non-adjustable, they just get torqued so indexing is not required when disassembling. That engine does use "torque to yield" head bolts which are not reusable. They stretch when initially torqued so you will need a new set. I think they're about $60.00/set.

I probably have a good rebuildable head if you find yours to be junk.

Good luck,
Rick"

"The only argument against a p

"The only argument against a piston problem might be that the tapping sound does not begin until the engine reaches 1500 rpm. It doesn't tap in idle. Seems that many of the threads I have read point to a piston if the noise is low on startup and then fades as the piston heats up. I know it's all speculation until the head is removed. Hopefully someone will call me back tomorrow who can look at it. At the moment, I'm kinda sick to my stomach wondering about the possibilities and definitely wishing that removing the head wasn't such a major ordeal."

There is no load on the piston

There is no load on the piston at idle and it's less likely to tap with no load on it. Let us know what you find.

"Hey Rick is right if you take

"Hey Rick is right if you take off the intake manifold you can remove the lifter, intake gasket is about $100.00 bucks. I just don't see it being the lifter. Hey Bill I feel for you I was sick to my stomach too, I am in southern California I don't know where you are but you can have any parts I have left over they are just going to the junk yard which is a shame because most of them are still good but the stuff is so heavy and bulky its hard to keep around just in case. Either way good luck. The 8.1 is great when it runs but expensive to replace, If you do need to rebuild or replace I can let you know the route I took and some of the prices."

"I removed the exhaust manifol

"I removed the exhaust manifold enough to stick my finger into the exhaust valve area. I noticed some significant differences in how the exhaust valve stem felt.

- #4 stem had all kinds of sharp crusty deposits on it. The other stems were smooth.
- The metal surface inside the exhaust chamber of the head was not smooth like the other 3. There was a curved area just above the valve stem that felt pitted with sharp edges.
- Obviously it's an exhaust path so it's going to be dirty, but #4 was quite a bit dirtier. I'm speculating that the lack of compression is due to the exhaust valve not closing fully due to deposits at this point.

So, I'm in the Bahamas and it's hard to find a gas engine mechanic. I was toying with putting things back together and pushing through a couple of bottles of seafoam deep creep through the intake manifold before I commit to the head removal. Maybe the deep creep will get the crud off the exhaust valve and solve the problem.

Thoughts?"

"I think that a stuck exhaust

"I think that a stuck exhaust valve makes a lot of sense. This would cause (a) low compression (b) high exhaust manifold temperatures since the combustion is essentially going straight out the exhaust (much higher temperatures than the exhaust gas only).

From what I've heard, people have had some success with using oven clean to clean stuck valves without removing the head. Has anyone ever tried this?"

"the way I see your problem,yo

"the way I see your problem,you are suffering from lack of performance,engine noise,overheating and deposit issues on both valve stem & spark plug on #4 cylinder.I think the task at hand is to come up with the common denominator with these symptoms in mind. Performance and compression go hand in hand but what is the cause of our low compression and can we relate it to the rest of our symptoms? So with upper engine noise, most likley excessive valve rocker to valve stem clearance for whatever reason,(faulty lifter or bent valve stem or a chunk of carbon under the valve seat( what makes the most sense )when you total the other problems into the mix. I tend to think that we have at least a sticking if not bent valve , this would explain the upper engine tapping also the low compression. this would also have to do with the performance of other cylinders due to contaminating air /fuel charges with incomplete combustion by products due to lack of complete aspiration caused by the #4 problem, also this could cause a general leaning of fuel to other cylinders creating a heating problem. I think it safe to say at the very least the affected head will need to be removed for evaluation and repair. Before doing any more disassembly I would strongly suggest a few more tests.I would perform a radiator pressure test with all spark plugs removed (this would serve to check the head gasket integrity somewhat) next I would do a cylinder leakage test whereby air is introduced into each plug port with the respective piston at top dead center and firing. at which point you would just listen for the air leakage exhaust,intake,crankcase,radiator this will help[ to isolate why you have low compression (bent valve/burnt valve/blown head gasket or whatever. just thinking out loud."

"Thanks Tom!

Additional inf

"Thanks Tom!

Additional information gathered tonight. I added radiator fluid because the plastic reservoir was empty. I ran the engine after using the deep creep. No smoke at all from the deep creep! I was amazed! Every video I've ever seen shows billowing smoke.

Anyhoo, I'm going to try "Bars Leak 3-Step Head Gasket Repair Kit". I have nothing to lose for $70. I've always had moderate steam coming out my exhaust and since I am losing coolant apparently and my coolant is a little milky/cloudy this is worth a shot. Worst case is that it does not work and I'll have to take the head off...which is where I am right now."

"Bill, just a word of caution.

"Bill, just a word of caution. anything capable of stopping or slowing down any head-gasket leak situation will unfortunately have a similar affect on other systems,Sensors and small passages like radiator core tubes and the like. It would be tragic to have to replace a engine but it would be horrific to have to replace engine,radiator,all sensors and related systems! Just saying look before you leap."

"All,

I completed the head

"All,

I completed the head gasket stop leak process. I used Bar's Leaks head gasket repair. I drained the radiator fluid, filled with water, let it come to temperature and repeated this process 3 times. I then followed the instructions putting the bottle into the radiator and topped off with water. Ran it at 1500 rpms for 20 minutes, let sit for an hour, drained and left open to the air for a day. Refilled and ran. I'm pretty sure that I could tell a difference with cylinder 6. The engine clearly loses rpms when I kill the spark on the #6 cylinder. #4 is unaffected and still generates very little compression.

I read through many different posts regarding exhaust valve cleaning solutions without removing the head. Most opinions center around using oven cleaner. The only gotcha appears to be concern over the effect of oven cleaner on aluminum cylinders. I have no idea if my 8.1GI has aluminum cylinders or not.

So I removed the manifold this afternoon armed with ezoff, a funnel and a small bit of tubing. I snaked the tubing into the exhaust port of #4. I sprayed the oven cleaner liberally. My hope is that it will seep down the exhaust valve and soak the area where the valve seals to the head. Ideally when I fire up the engine the next time, a bunch of junk will blow off and I'll have some sort of seal there again.

So, I'll have some answers in the morning. If nothing else, I believe I will have eliminated head gasket and exhaust valve as issues. Of course it's possible that the oven cleaner is not strong enough to remove all the buildup from the exhaust valve. I also suppose that it's possible for the exhaust valve to be bent, but if the exhaust valve was bent, wouldn't the pushrod on the other side of the rocker likely be bent too? I'm able to move the exhaust valve up and down with about 130 lbs of downward force (me pushing down with a bunch of my weight with a small block of wood)."

"Bill, just read your update.

"Bill, just read your update. I hope for the best for you but I think the other is most likley. I think your on the right track with the valve. One possibility is that the affected cylinder could have carbon deposits to the point that the valve and piston came in contact causing the valve stem to bend and not affecting the push-rod. Remember the class action suite I mentioned about your engine having a known defect due to excessive clearance between piston and cylinder wall allowing excessive piston slap to the point of the piston skirts braking off. I tried to reach you on Skype but could not connect, best of luck let me know if I can help. Had a good visit with Casey over the weekend."