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Help needed - Engine still running hot

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Rugger8
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Help needed - Engine still running hot

Post by Rugger8 » Wed Dec 09, 2009 11:57 am

Ok, as many of you know, I have been completely rebuilding my Hercules WB engine, because it overheated this summer. Well, the #2 piston melted and the head warped. In any case, I rebuilt most of the engine, with new pistons, new rings, redon valve seats, etc. Well, I put the engine back together and back down in the bilge and started her up. She sounds great and water is coming out of the back end in whooshes as it is supposed to, but she is running hot still. Around 200 degrees when she should be running around 150. The water coming out of the muffler is not hot, it is luke warm at best. So, it seems to me that the most likely culprit is a rusted out exhaust manifold that is either blocked up or rusted through so that the water does not go all the way up the manifold. Any thoughts or ideas on other possible culprits would be greatly appreciated. BTW, the impeller was checked previously and looked fine (replaced it anyway). I also backflushed the intake house and that did not indicate and blockage.

Thanks,

Jeff

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Thermostat??

Post by evansjw44 » Wed Dec 09, 2009 2:52 pm

Does your WB have a thermostat? Thermostats can be piped a number of different ways but I beleive the WB like other CC flat head sixes wasn't born with one. Typically the thermostat bypasses the cooling water out of the block directly to the water discharge. Typical CC 6s have the cooling water enters the block through holes in the lower passage of the exhaust/intake manitfold through holes in the manifold that mate up with holes in the block. Maybe you need to make sure those holes line up? Discharge water exits the cylinder head at the front and is piped to the top of the exhaust/intake manifold then through a passage in the exhaust elbow that mates up with the manifold. Note, Ks don't have the upper passage, just Ms and Ws. When you introduce a thermostat the ones I've seen block the discharge of water out of the head and allow the water in the manifold lower chamber to dump directly overboard. Your could be different.


Another possibility is that where you have the temp guage pick-up/sender could have an air pocket. My generator is that way. I have to loosen the sender and bleed off the air to get the temp balanced in the block.
Jim Evans

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Post by Rugger8 » Wed Dec 09, 2009 3:08 pm

Jim,

thanks for the response, I am going to post some pictures of the engine and exhaust manifold as this will probably help with the discussion. I do have a thermostat and it resides at the forward edge and top of the exhaust manifold. I thought the thermostat might be bad, so I took it out and re-started the engine and it ran at the same temperature around 200 degrees. So, that did not appear to be blocking the water flow.


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Post by Gord » Wed Dec 09, 2009 4:17 pm

Does the engine make a pinging sound under load, when was the last time the distributor was rebuilt, what spark plugs are you running. A hot engine will not melt a piston, an engine that is detonating will, detonation is caused by timing or extreme carbon build up on the tops of the piston. If you are not using the right spark plugs, if your timing is not correct, if your engine is detonating no amount of water will cool it. If your distributor is allowing to much advance its going to run real hot, either initial advance or centrifical advance is probably your problem. If it melted a piston your problem is detonation not a cooling system problem.

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Try

Post by evansjw44 » Wed Dec 09, 2009 4:23 pm

Try disconnecting the water discharge hose that goes from the cylinder head to the thermostat. Water should just gush out when you run the engine. And, there shouldn't be any water going out the exhaust, I don't think. I don't know for sure but its possible that if you put the head gasket on upside down or backwards it might block water flow. Still, I don't see how you get exhaust cooling water but limited flow, if any, through the block. I could use a picture of the from of the block. I had the same thermostats on my model Ms years ago. They never worker right for me. I wonder if you have the original manifold end plate without the thermostat.

I'd check the water out of the head before I did anythig else.
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Post by Gord » Wed Dec 09, 2009 5:48 pm

Good point Jim, I would like to see a picture of the melted piston, that would help in determining the problem. To melt a piston you have to be talking temps between 1500 and 2000 degrees. Those are temps found in the cylinder during the compression stroke, an over heated engine will cause severe scoring of the cylinder eventually and head gasket failure would normally occur before that, warping of the head etc would follow. But 200 - 300 degrees will never cause the melting of a piston thats a whole new ball game. I am wondering if the centrifical advance in the disributor is stuck in full advance mode, that alone can cause exhaust temperatures to be really high, sometimes high enough to burn a valve or start the detonation problem.

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Melted Piston

Post by evansjw44 » Wed Dec 09, 2009 6:32 pm

A meleted or holed piston is from running way too lean or detonation. I agree that just overheating would do that. The piston might sieze in the bore and break a rod but not melt. There a lot to play with here. The Ws I saw years ago had variable high speed jets. If you set one too lean you might burn a piston. Also, you mentioned detonation. Might be possible as a W doesn't have timing marks to set the timing to. It would be easy to set the timing too far advanced. That might be OK if you only ran at low RPM but if you picked up the revs you migh detonate a lot and burn a piston.

I guess I'd like to know which cylinder had the burned paiton. I'd also like to know about cylinder scoring.
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Post by Rugger8 » Wed Dec 09, 2009 8:53 pm

ok, thanks again Jim and Gord. The engine does not sound like it is detonating, it actually sounds good and smooth. The piston that melted was in the second cylinder. There was some light scoring from that, but it was able to be honed out. I actually had a machinist out to the boat to check the engine out and he indicated that none of the scoring was bad enough to even need a re-bore, just a honing. I am attaching pictures of the piston, but I don't have a view from the top.
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I am using J8c spark plugs. They are not new as I figured they might get fouled on restart up and was going to replace after that. The distributor was rebuilt about 3 years ago.

Jim, not sure exactly what part of the block do you want to see. Can you say that again.

Thanks,

Jeff
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Post by THE RAZZ » Wed Dec 09, 2009 11:46 pm

Jeff,
The skirt above to top (compression) ring is scored- see the galling lines. Apparently 5 pistons are Ok.

I agree with Gord re temperatures needed (about 1220F) to melt an aluminum piston. The problem is, more than one cylinder should have detonated if its timing. Melting one cylinder but not others is odd.

Re lean mixture- usually running lean glazes cylinders and dramatic blow by follows. Usually several cylinders glaze when there's a lean mixture. 2 Carbs usually glaze 3 cyl 3 carbs usually glaze 2 cyl etc.etc. A badly glazed cylinder will allow enough blow-by to raise the crankcase pressure high enough to force the mushroom-capped dipstick out of the filler tube. Massive blow-by makes it look like a steam train venting.

A runabout is easy to dynamically time when in doubt. Go to full throttle on a plane. If the engine rattles, go to idle. Adjust distributor until tach drops 100 rpm. Repeat until there is no "rattle" (detonation. Zero tolerance for the "rattle."

No idea how to dynamically tune a cruiser.
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Melted?

Post by evansjw44 » Thu Dec 10, 2009 7:33 am

I certainly see a lot of scuffing and scoring on that piston. Without seeing the top I can't call it melted. I might more consider it scuffed, maybe by a frozen wrist pin. If the pin was siezed I'd expect to see scuffing more on the edges opposed to the pin an less near the pin. Maybe the oil feed went dry?

I don't see how the middle cylinder of a group of three fed by the front carb would go lean without burning the end pistons first. End cylinders run leaner than middle cylinders. These manifold have pretty primative flow patterns. More like pipes than flow races.

At this point I bet my doughnut on a stuck wrist pin or loss of lubrication. You have something else blocking water flow. Maybe a head gasket or a manifold to block gasket blocking flow. I want to hear what pulling off the discharge hose does. I can't remember the flow pattern of the thermostat body. I think it allows water in the bottom of the manifold (inlet) to exit the top of the manifold (outlet) bypassing the block. The thermostat opens and allows flow through the block to mix with the discharge water. Maybe the thermostat is in upside down? Did you replace the 'stat when you rebuilt the engine?
Jim Evans

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Post by Rugger8 » Thu Dec 10, 2009 9:59 am

Thanks guys. I am going to do the tests on sunday, when I have a little help. I am also going to use an infrared laser point thermometer to test the temperature at different parts of the head and exhaust manifold. Here are some pics of the piston in the cylinder before I took her out. Also, there is a small crack on cylinder 3 that was repaired with stitch welding by some previous owner. The machinist looked at this and thought it was ok, could go bad, but he thought it was worth trying first rather than replacing block. There was no water in the oil, so does not look like crack went all the way to the water jacket.

Jeff
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Post by Rugger8 » Thu Dec 10, 2009 10:04 am

here's the #2 piston in the cylinder.


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Water Damage?

Post by evansjw44 » Thu Dec 10, 2009 11:30 am

How about cracks in the head over #2 cylinder? Maybe water leaking from the block crack is the cause as well. I can see where water leaking into the cylinder could do that kind of damage. It makes steam during the power stroke that reacts with the aluminum to errode the surface.
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Post by THE RAZZ » Thu Dec 10, 2009 1:52 pm

Jeff,
The pic helps here.
Remember- you CANNOT compress water/oil/gas...... per fluid dynamics. Vapor will, liquid won't.

So, if that gasket leaked while she's sitting, on the first compression stroke when starting, #2 will either bend the #2 rod or break #2 piston.

This engine should of had massive blow-by. The #2 cylinder vented +/-130 psi through the piston hole into the crankcase. While the crankcase psi is normally a few psi, this crankcase psi would be so high it should blow the dipstick out of the oil fill tube.

Re the crack- there's no water at this spot where it cracked. That space between the exhaust (smaller) valve and cylinder is solid and uncooled which is what can cause the block to crack at that spot.

Have the machinist sleeve that one cylinder. Bore it .190" over. Ask him to leave a .125" lip at the bottom of the cylinder for the sleeve to sit on. The tight fit sleeve is then trapped between the head and lip. Nice safety feature.

If this block has valve seat inserts, that crack will loosen the #2 exhaust seat. When its loose, it will breakup. Usually they blow out the exhaust. When that happens, the 6 cylinder engine becomes a 5....... instantly.
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Post by Gord » Fri Dec 11, 2009 4:35 pm

I see signs of serious detonation, my guess timing is the issue, flat heads do not make a lot of compression
so you may not hear it like you would a modern OHV engine. I would put it back together and mechanically set the timing by finding TDC on the compression stroke on #1 cylinder. I would advance the timing a little at a time when you start to see the heat come up then back the timing back down. Detonation will burn or melt the side of the piston first and work its way to the center. By the time it starts to move towards the center the piston fails and catastrophic damage occurs. I think you may have found your problem. My experiance over the years is that a lean engine shows up first on the plugs, If the porcelan areas of your plugs is white or peppered then you are lean. But the failure of a single cylinder is a very strong indication of a severe detonation problem, and over heating is just a symtom. I set my rich & lean with a simple 02 sensor, remember lean is very bad always run on the rich side.

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Post by Gord » Fri Dec 11, 2009 4:46 pm

Water or steam would never cause this king of failure you would actually have a steam cleaned cylinder as a result of water being intruduced into the clylinder. In fact on many high compression gas or diesel engine you will see water injection systems that feed water into the combustion stroke to help control detonation. You may find the damage to the piston is on the exhaust valve side, it is not always the case but the melting is caused by super heated exhaust gas. On a non water cooled exhaust manifold I can turn it cherry red in a matter of seconds just with timing. Again these old engines do not make a lot of compression so timing is critical.

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Post by THE RAZZ » Fri Dec 11, 2009 8:11 pm

Gord,
Lets agree to disagree re liquid being able to collapse a piston. Micro amounts of water won't. But a leaking headgasket dripping water over time could drip more water than space in that #2 cylinder.

If that happens, the piston will collapse. Water will not compress in a liquid state When the engine is cold as in starting its possible to have more water than space. Something would have to give- the piston or head would probably be first.

Damage seems to be limited to #2 cylinder. We should see other signs of detonation in 1,3,4,5,and/or6. Onward.
Jerry Turney
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Curious?

Post by evansjw44 » Fri Dec 11, 2009 8:16 pm

I look at the pictures and I see carbon on the top of five cylinders but not on number 2. I agree water injection is used to control detonation, like the Olds F-85 with a turbo in the late 60s or early 70s and the P-51 Mustang Allison, too much water injection will errode aluminum pistons. We used to dump water down the carb to de-carbon our high compression engines in the late 60s and early 70s. I had a 70 Merc with a 351 Cleveland with 11.2/1 ompression that needed regular water treatments to keep from pinning.

Anyway, that #2 piston is the only one damaged so I don't see detonation as the cause. More than one piston would show damage. I still like water injection into #2 cylinder as the cause. Blown head gasket, cracked head, block crack if it goes into the water jacket, or maybe a crack in the exhaust manifold where the intake passage passes through it.

Maybe some more checking. I'd have the block sleeved too. That crack is going to go right down the cylinder wall and leak water into the bore.

But you're right, fill the cylinder with water and you'll hydro-lock the clinder and maybe break or bend a rod. OUCH
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Post by Rugger8 » Fri Dec 11, 2009 9:40 pm

Can't say I can follow everything that has been said here, but I am learning quick. It definitely does not make sense to me that piston #2 would be damaged and #1 and #3 pistons would be fine, since they are all running off the same carb. As a note of further information, when it overheated before taking it off there was water/steam coming out of the #2 sparkplug hole. originallly thought there was a crack there, but after magnafluxing, etc. there was no crack. However, the head was warped roughly 20/1000 out of plane. So the steam was escaping around the head. That may have relieved the pressure before #1 and #3 pistons were damaged. I will be laser spot temp testing the engine on sunday/monday. Are there any specific areas I should concentrate on?

Thanks,

Jeff

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Post by THE RAZZ » Sat Dec 12, 2009 2:11 am

Jeff,
My guess is the gasket leaked for "x" reason. It continued to leak while sitting. At some point it leaked enough between runs that water then sat on the piston.

When the engine turned to start after sitting, the volume of water exceeded the volume of the combustion chamber- Bam.... something had to give.

Hydraulic lock (on startup) cracked the piston. Running with the cracked piston further destroyed it.

The engine should have been streaming massive blow by out crankcase breather pipe and dipstick tube.

Some remember mechanics pullling radial engine props through 4 blades. That was to clear cylinders of oil to prevent hydrolic lock. In that case, radial Cyls 4 5 & 6 (bottom cyl) would drain oil down to the top of the pistons through valves and guides while sitting overnight. Oil, like water, won't compress. The fear then was starting a radial without 4 blades could bending a rod. On a radial that could ruin your whole day.
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Post by Gord » Sun Dec 13, 2009 7:24 pm

The damaged piston is clearly caused by detonation no question about it.I have seen it many times. The fact it occured on only one cylinder is not un usual in fact its the norm. rarely will detonation damage several cylinders. The damage to that piston was not caused by steam, water or a cracked head. Certainly simple physics confirms a liquid will not compress but there is no way water or any liquid created the damage seen on the piston. This is one of the clearest examples of detonation destruction as a person will ever find

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Post by Gord » Sun Dec 13, 2009 7:36 pm

I can assure you the piston will never show this type of damage by hydraulic action of water in the cylinder its simply not possible, first of all the starter would not beable to crank if a clinder filled with water on the compression stroke, the failure that would occur when a cylinder hydraulics is a bent rod. The rod is by far the weakest link and would bend way before any damage to the piston would occur. The damage is clearly caused by heat it is in fact caused by super heated exhaust gas. In my 25 years of racing and building & destroying racing engines I can assure you this damage was not done by water.

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Post by THE RAZZ » Mon Dec 14, 2009 10:36 am

Gord.
Ok. You've seen more detonation damage than I have. Can't argue with that.

That spark knock (rattle) that lead to the detonation must have been pretty loud. The hole in the piston must have created terrific crankcase pressure. The blow by in the engine compartment must have been something.
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Post by Gord » Mon Dec 14, 2009 11:48 am

Jerry , flathead engines of this vintage have very low compression right from the start. This would of made the noise created a lot less than you would think. Its not at all like you would hear from a conventional engine. There would of course been blowby but again the crankcase pressure in this engine is vented not just by the engine vent tube but also through the transmission vent as well. I know the dipstick on my Chrysler requires a little bit of a tug to get it out so its possible there is not enough pressure to push the dipstick out. I have been wrong before but this sure looks like a clear case of detonation to me. :)

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Post by THE RAZZ » Mon Dec 14, 2009 3:30 pm

Gord,
This makes sense to me
.
Wouldn't you expect +/-100 psi from this engine?

My experience with Hercs is limited to the K series. I had no idea this engine we are talking about was vented (2+ filler tube) from the tranny also. Of course,in the case of the K series trannys and engines, share the same oil. The K series has just one vent- one from the valve cover to the carb plus the 2" dipstick tube.

On the Razz engine , two cylinders glazed from sloppy carb jetting. We were running 2 of three carbs on a .060" main jet and one on .050." Cly 5 & 6 glazed and the 100+/- psi blew the dipstick out of the oil filler tube. Hell of a sight not to be forgotten.

Fortunately, we got home safely, but the repairs did use use up a little of the lunch money, if you know what I mean.

Jerry
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#2 Piston

Post by evansjw44 » Mon Dec 14, 2009 3:50 pm

#2 piston has a cavity erroded in it but it doesn't look like its through the crown to me in the picture. I agree with Gord, it could be detonation. But my thought of water ingestion seems lost here. I'm suggesting that the water is being ingested during the intake stroke and not just dripping in while the engine is at rest. That's why I suggested a perferation of the intake manifold passage. At rest water wouldn't just drip in, at least not enough to hydro-lock the cylinder. I've seen cases of this on CC v8s where the intake failed. Remember, the intake passages are surrounded by water jackets. So, I'd take a close look at the intake runner feeding #2 cylinder or possibly the gasket between the manifold and the block where water could get into the cylinder by passing between the #2 cylinder intake port and the water jacket hole nearby. As least that would explain the steam when the plug was pulled out.

I had my generator have a develope hole in the cylinder head that allowed water in the cylinder. It never hydro-locked but it fouled out the cyinder.
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Post by Gord » Mon Dec 14, 2009 4:32 pm

Jerry you are right when that dipstick comes out of the tubed it can have some force, not to mention the mess. This engine compartment must of had some serious blow by vapor in fact that oily mist is probably everywhere. The owner may want to keep her out of any dust till she's cleaned up. On our race engines we use an actual vacuume pump to create negative pressure and pull fumes from the engine those fumes are not just messy under the right conditions they can be explosive. Add to the mix a liberal dose of Nitrous Oxide and the cylinder pressures are very high. Last year I had a failure where the fuel solonoid on the nitrous system failed at 7500 rpm by the time I figured out what happened she leaned out and melted two Keith Black hypertectic pistons, it took just seconds at that rpm.

In any event this was a great discussion with many good solid ideas with respect to the cause of the over heating and the piston failure. :)

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Post by Gord » Mon Dec 14, 2009 4:46 pm

Jim I can understand how the water could play a part. We used a head on a 300 Ford six race engine that was ported to the point the water jackets would seep into the engine when the engine was off. As soon as we turned it off we would have to drain the water from the cooling system. When fired we would add the water back in. Certainly some of the water made it into the cylinders but it never created any problems. That head is no longer used we were able to find a way to speed up air fuel mixture velocity with a differnet intake set up and there was no longer a need for such radical porting. On Nitrous my current 300 inline six makes more than 100hp per cylinder and almost 780 ft lbs of torque and yes its normally asperated.

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M onster Six

Post by evansjw44 » Mon Dec 14, 2009 6:48 pm

OK I've not heard of anyone hopping up a 300 inch Ford six. But then why not? 600+HP out of one of those is a stitch. I don't know how many friends I know that tried to beat that Ford six into submission and failed. The car/truck failed first.

Like my generator, the clue was the piston was spiffy clean on top when the others were carboned up. My generator has steel pistons so water won't hurt them. Too much water injection on aluminum pistons causes errosion.

I'd like to really go through that old WB with my machinist but its not my engine. Maybe I'm glad its not my engine.
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Post by dalesparrow » Mon Dec 14, 2009 6:49 pm

sounds like thermostat is faulty.On WB engines the thermostat starts out open allowing water to go from the bottom of the exhaust manifold directly to the top of the manifold and out your exhaust without ever going through the block, as the engine warms up the thermostat closes forcing water through the block.Qn my WB engines I have removed the thermostats and pluged the holes that they sat in with brass plugs. This forces the water to always be going through the block.Hope this helps.Dale

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