roule

roule

Active Member
Hi , new post for my RRC EFI 3,9 with the good title ;)
I have a question and a concern about a vertical mark on one of my cylinders, it is not a scratch, it is extra thick, as if a weld had been made. My compressions are correct (12,5 bars) and the engine is not knocking. Any idea what it could be? A part of the camshaft that would have come loose and been crushed by the piston?
IMG_4766.jpg
Capture.JPG
 
Not an overhead camshaft engine so unlikely to be a bit of that.
Anything getting there from above would have to have:
1. Been left in there when the heads were last off.
2. Been sucked in through an inlet valve.
3. Be a bit of the head of an inlet or exhaust valve.
4. Be a bit of broken spark plug.
5. Be a broken bit of piston ring.

But I would expect any of those to leave a groove, not a raised vertical ridge.

The rings being all in line might be a possibility.

The bore looks quite pitted & there looks to be a horizontal ridge towards the top of the bore.
This appears to be heavy wear, perhaps it should have had a rebore & not just the rings changed.

If you didn't do the ring replacement you have no way of knowing what state the bores were in when the rings were changed.
 
+1 on all rings inline & not able to rotate. The "rebuilder" should clean the ring grooves, but if they didn't then they could have become stuck. This could certainly leave a ridge in the cylinder as the remainder wears with use.

That said after only 2000 miles, there should be very little wear.

I would pull that piston out and check the rings.
 
If that is only 2k miles after a "sort of rebuild" then it don't look good.

What else was supposed to of been done when new rings were put in?
I would of expected a hone, and that don't look like a good 1.
And also to mention from your other thread, Liner height looks questionable., Why did you take it apart?

J
 
marjon said:
Si ce n'est que 2 000 milles après une "sorte de reconstruction", alors ça n'a pas l'air bien.

Qu'était-il censé faire d'autre lorsque de nouveaux anneaux étaient installés ?
Je m'attendais à un bon, et ça ne ressemble pas à un bon 1.
Et aussi pour mentionner dans votre autre fil de discussion, la hauteur de la doublure semble discutable. Pourquoi l'avez-vous démonté ?

J.
Click to expand...

The truck hasn't been driven much in ten years, after replacing the rings and honing the bores.

I opened because I had gasoline in the oil (leak from the injector ...)
and i suspect a manifold leaking too. Then i replace the cam and the lifters as 2 lobes lost material (bad aftermarket camshaft i imagine)
 
pwood999 said:
+1 on all rings inline & not able to rotate. The "rebuilder" should clean the ring grooves, but if they didn't then they could have become stuck. This could certainly leave a ridge in the cylinder as the remainder wears with use.

That said after only 2000 miles, there should be very little wear.

I would pull that piston out and check the rings.
Click to expand...
Someone already pull of the piston (and replace rings) without removing the block ?
 
I had 12,3 bars on this cylinder , i imagine i should get a little more after valve laping (littl bit rusty)...
 
roule said:
Someone already pull of the piston (and replace rings) without removing the block ?
Click to expand...
I have done it on several cars (although not a RR). Take the sump off (after draining oil !!), and you should be able to undo the big-ends & get the pistons out. With the big-end removed, just tap the piston from below using a piece of wood. Label the pistons as they come out, so you can get them back in the same holes !!

Check you have a working piston ring compressor before you do it though !!
 
Hi mate as the guys have said bores don't look honed to me, would be concerned about the pitting, is pitting in all cylinders excluding the ridge? typical of standing, as said above would look a little futher
 
I thought it looks like a rust mark, that been cleaned off. Especially how it looks like a puddle formed at the bottom?

Maybe the head gasket leaked a dribble and it sat and rusted the liner.

All the other marks look a lot like moisture damage, from sitting, at some point.
 
Yes the truck was standing (or drove very little in ten years) after the engine was partially rebuilt (new rings , bores honing, rods, camshaft). I open it because of injectors leaking (gasoline smell in the oil), this must explain the marks on the cylinders wall (almost the 8 ). I intended to use brake cleaner to erase theses marks and fill each cylinder with gas oil , and turn the engine by hand, in case the segments are little stuck...
Few photos just after opening...thanks a lot for the help.
IMG_4280.jpgIMG_4282.jpgIMG_4284.jpgIMG_4285.jpg
 
Last edited:
Here i the piston 8 : rings are good. I notice very little pieces of metal, probably the chinese camshaft sitting since 10 years ...so littel scratchs on the piston too (i can not feel them with the nails). I don t want to remove the block. I wonder if i should hone the

IMG_4776.jpgbore (with good protection on the crank) IMG_4778.jpgIMG_4779.jpgor let it like this ...IMG_4777.jpg
 
Were the ring gaps lined up when you pulled the piston ?

With the heads off, pulling the block is only a small extra step. Besides, unless radiator is out, you cannot change the cam with the block in place. Having gone that far, it's best to do it properly.
 
pwood999 said:
Were the ring gaps lined up when you pulled the piston ?

With the heads off, pulling the block is only a small extra step. Besides, unless radiator is out, you cannot change the cam with the block in place. Having gone that far, it's best to do it properly.
Click to expand...
The rings where not lined up,but only 5 cm gap. The new camshaft is already in place...and it's an automatic gearbox.
 
There appears to be a faint bronze colour showing on the shells in your photos, esp the top one.
If that is the case they are worn & getting to the end of their useful life so need replacing.
Use a micrometer on the big end journals to check for any ovality.
 
Ratae said:
There appears to be a faint bronze colour showing on the shells in your photos, esp the top one.
If that is the case they are worn & getting to the end of their useful life so need replacing.
Use a micrometer on the big end journals to check for any ovality.
Click to expand...
I see what you mean but i think it's a trick of the light?
 
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