ceramic coated piston top

[LiquidX]

Well, I went out and did some spirited driving and after it was all done I'm smoking like a freight train and there is a loss of coolant as well. Today I did some testing and 155 across the board for compression minus cylinder #3 which was at 65. Cap of oil took it to 125.

I now know that either it's bad rings or a busted ring land or two at the least. I currently have the Mahle pistons and when I got them they were ceramic coated by MAPerformance.

Is it making a large difference by coating it rather than having it un coated in the case of a new piston is needed?

 

[RBehne2]

Might be a hairline crack in the head gasket. Can you do a leakdown on that cyl. 3, with a coolant pressure tester installed?

 

[LiquidX]

The cap of oil would determine if the problem was bottom end or not. If the pressure test remained the same after the oil was put in then it would deem the top end (HG up). Since the pressure increased with the oil then it's sealing up an issue located on the piston which would either be ring/s, land/s, cracked piston.

 

[delta448]

I am not sure it's quite so clear cut on the oil test, but you're right, it indicates the problem is much more likely in the bottom end. I'd still do the leakdown test before I pulled the head though.

Is it making a large difference by coating it rather than having it un coated in the case of a new piston is needed?

I can't speak from experience on this, but my gut feeling here is that yes it does matter. The real question is how much will it matter... you will just have to keep in mind that this cylinder will handicap the rest if you skip coating it.

 

[razrman8]

What exactly is the point behind ceramic coating the top of the piston do?

 

[Rob10_99]

Less thermal load on the surface, keeps more of the heat in the chamber than if it weren't coated. More pressure and heat is good.
Might save the piston if you run lean for a short period as well.

 

[razrman8]

Less thermal load on the surface, keeps more of the heat in the chamber than if it weren't coated. More pressure and heat is good.
Might save the piston if you run lean for a short period as well.

Thanks for the insight.

 

[LiquidX]

Yeah Zach I see what you are saying. Before I do any head pulling I am goi to have the mechanic who actually built the motor just give it a one over. I'm sure he would want to see what happened and give his input as well. He has a leak down tester anyway unlike myself.

I contacted MAP via email and will get a reply sometime later this week. They no longer list the Mahle 8.5 CR pistons as they just show the 9.0 and 9.2 CR pistons.

 

[keltalon]

Well, I went out and did some spirited driving and after it was all done I'm smoking like a freight train and there is a loss of coolant as well. Today I did some testing and 155 across the board for compression minus cylinder #3 which was at 65. Cap of oil took it to 125.

I now know that either it's bad rings or a busted ring land or two at the least. I currently have the Mahle pistons and when I got them they were ceramic coated by MAPerformance.

Is it making a large difference by coating it rather than having it un coated in the case of a new piston is needed?

One way to tell if its the rings is to crank the engine let it warm up and see if smoke is coming out of valve cover and dip stick if it is then its the bottom end, next remove the spark plug from #3 then crank engine again the smoke should stop coming out of the dipstick and valve cover. leave the spark plug out.

 

[Kickerbeast]

I wouldn't take a risk of running it if you think the ring is broken. If the chunk is small, it could get lodged and destroy the cylinder wall. I would just do a leakdown test. It will tell you where the compression is going and there is not risk of further engine damage.

 

[LiquidX]

Exactly, I have already determined the same smoke is coming from the oil cap and out of cylinder #3. The only person that is going to start it up now is the builder as he will take responsibility if starting it and two should know better not to anyway to prevent further damage.

 

[99gst_racer]

Scott, are you 100% sure the piston tops are coated? For most off-the-shelf 4G pistons., it's usually the skirts that are coated when someone refers to "ceramic coated pistons". Unless yours were specifically coated on the tops as well...

It probably wouldn't make much of a difference to run one un-coated and the rest coated, but if it were mine, I'd just send that single replacement piston out to get coated to match the rest. That way your piston temps and cylinder temps are all more even and uniform. I doubt it would make a huge difference unless you were on the ragged edge, but it could potentially pose as a tuning nightmare if you were.

 

[LiquidX]

I bought the pistons from MAP and had them coat the tops. I have pictures of them in one of my journal entries if you are interested. It seems I will go and get a new piston coated if that is in fact the issue. I won't know for sure until the piston comes out if it's the rings or lands.

 

[99gst_racer]

10-4

So, when does the tear-down begin?

 

[LiquidX]

Well, hopefully sooner than later

I talked to the builder and he does want to look at it and the earliest I can get it to him is on Wednesday due to an ice storm that is supposed to happen tonight. After that I'm praying that it will begin shortly after.

Truth-be-told, I've never done a tear down like this for new parts to be installed. I've torn apart a motor that was already out of the vehicle. I just really suck with measurements and math

If at all possible for me to learn and be under a supervised eye, I'm going to try and see if the builder will let me do some of the work with him going over it with me. I just cannot afford downtime right now as it's my DD and only vehicle.

Not to mention I do believe I need to get the transmission pulled and sent out to Jacks to have them go over it as well for the reverse issue I'm having which is discussed on another thread I have going.

 

[keltalon]

I wouldn't take a risk of running it if you think the ring is broken. If the chunk is small, it could get lodged and destroy the cylinder wall. I would just do a leakdown test. It will tell you where the compression is going and there is not risk of further engine damage.

Lodge and destroy a cylinder wallWTF if the ringland is damaged how in the WTF will it destroy the cylinder wall? Regardless if the ringland is damaged the proper way to fix it is to take it out and have the block machined with an oversized piston! My $.02

 

[Kickerbeast]

Lodge and destroy a cylinder wallWTF if the ringland is damaged how in the WTF will it destroy the cylinder wall? Regardless if the ringland is damaged the proper way to fix it is to take it out and have the block machined with an oversized piston! My $.02

I was referring to the ring itself, not that land. Either way, if there is a chunk of the ringland or a chunk of ring sitting there bouncing around while the engine is running, either could get pulled between the piston and wall and damage both. I've seen both happen before, more often in off road, but it can happen none the less. I was just trying to ensure the OP didn't do any further damage to the engine. A leakdown test will give you the information without risking it.

Yes, I agree that if it is a broken ring or piston that the engine will need a teardown and likely blockwork. Lets see what comes out of the test first though.

 

[keltalon]

I was referring to the ring itself, not that land. Either way, if there is a chunk of the ringland or a chunk of ring sitting there bouncing around while the engine is running, either could get pulled between the piston and wall and damage both. I've seen both happen before, more often in off road, but it can happen none the less. I was just trying to ensure the OP didn't do any further damage to the engine. A leakdown test will give you the information without risking it.

Yes, I agree that if it is a broken ring or piston that the engine will need a teardown and likely blockwork. Lets see what comes out of the test first though.

Thanks for clarifying Get that car running soon summer is just around the corner.

 

[LiquidX]

Found out what the issue was. The #3 top compression ring got stuck in the ring land in a "closed" position effectivly not allowing to seal for compression. It was also the cause for the excessive blow by smoke. On top of that, all pistons are starting to show signs of melting so I'm replacing all of them.

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A #3 intake valve spring seat also shattered into 4 pieces which was found in the pan.

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Cylinder walls are great and so are the bearing surfaces. I'm just going to replace them and polish the crank again since it's all out and know there isn't going to be a problem down the road.

All-in-all I'm doing new pistons, HG, bearings, and going to replace all 16 spring seats since they are all the originals.

 

[Strm Trpr]

Those melted areas looks like they started right where the intake valve reliefs are cut into the piston crown.
Those very thin spots got extremely hotter and began melting.

Those thin valve reliefs need to be hand dressed and removed due to this very thing.

The top ring looks to have mirco welded itself to the ring land.

When you put the new pistons in, make sure and remove those thin spots on the piston crown.

This looks like a high compression Honda piston, but you get the point.

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[99gst_racer]

Scott, that looks like a retainer in the bottom of the pan. The only way a valve seat could get into the crankcase is busting it's way through a piston.

 

[turbo23]

While you have it apart, it'd be a good idea to check the cylinder bores for size. That much detonation will deform stuff, I'd also get rods checked for size. I'm really wondering whats in the pan. it looks like a retainer, but if a retainer broke the valve would get pulled into the chamber and would break. a valve seat wouldn't have anyway to get to the pan with out going through the piston either.

 

[LiquidX]

All the retainers are intact as far as I could see.

How would a spring seat have to get through a piston when it's sitting directly underneath the spring in the head? If it ends up shattering for an unknown reason it could bust into pieces (see above) and fall down the oil return passages in the head straight to the pan.

I did order a whole new set of 16 seats however.

 

[99gst_racer]

Your spring seat is below the spring, but your valve seat is in the combustion chamber.

If all your retainers are intact, then I don't know what that is in there. You should fish out the piceses, clean them up, and take close-up pictures. It looks like it was round and stepped, so it sure looks like it could have been a retainer.

 

[LiquidX]

AH HAH. I put in the wrong word on the update. I meant spring seat not valve seat DOH! Let me go edit that