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FYI, burning oil most likely does not come from the lower end, but from the valve stem seals. They all leak a bit, some less, some more but that's the main culprit for 99% of these engines not the rings.
FYI, burning oil most likely does not come from the lower end, but from the valve stem seals. They all leak a bit, some less, some more but that's the main culprit for 99% of these engines not the rings.
Ah! I learned something. Thank you
You are correct. I had a look at the cylinder head. I found lots of oil build up around the valves. Fortunately, the stem seals are still available so those will also be replaced. It just keeps pilling up eh?
All the stems had significant amounts of oil present. I have no frame of reference and a little is expected Exhaust vs intake valves. I assume gasoline/air mixture cleans the intake side. Impressive amounts of crude on the exhaust ports. Also the engine slants towards the exhaust side so oil naturally accumulates more on that side intake valve exhaust valve all of the pistons had a shiny spot near the intake valves. I assume that's from the cleaning action of gasoline
Nice find! It doesn't say what grade they are but looking at the listed dimensions and the document I posted above, they seem to be "white"...which is what I need. I contacted them and they are working on my parts, fingers' crossed!
Side note: I am beginning to see a pattern. Most of the well known parts suppliers seem to be getting their parts from some German company called "limora". In the past I have bought parts from various North American suppliers and the customs paperwork always lists "limora" as the supplier. The curios thing is that all the known suppliers offer the same "limora" parts for different prices but when I myself go to limora's website, I see extremely high price points, I wonder if there is some sort of backdoor deals the big players get. Anyhow, this listing also pointed to "limora" after I contacted them...
if they don't have them, I think the next logical thing would be to find a lower mileage engine from an auto yard...or have custom ones made, which is likely uneconomical, even if it was offered
If and when you get the bearings, can you also measure the width of the shells? Question is referring that if I recall correctly Pontiac used 3 inch main bearings in 400CID (and maybe 389, can not remember) motors. Tap placement, oil hole and all of the other would be appreciated also.
If and when you get the bearings, can you also measure the width of the shells? Question is referring that if I recall correctly Pontiac used 3 inch main bearings in 400CID (and maybe 389, can not remember) motors. Tap placement, oil hole and all of the other would be appreciated also.
they didn't have them but I can get you the dimensions from the current bearings I have. Would those help?
also interest are if there are thrust bearings (maybe the item 2 marked thrust washer in the diagram) the dimensions of those.
thanks in advance
I hope these help. Let me know if you need other dimensions. I would take the measurements with a grain of salt. It's hard to accurately measure curved surfaces. All measurements are in mm
centre (one of those in the block, thick) bearings vs main bearings (6 of those in the block, skinny) main bearing main bearing main bearing bottom side of main bearing and cap main bearing (not the two holes, one lines up with in the block, the other one does not...likely for relief) main bearing location in block (note one hole for oil) main bearing centre bearing (not the two holes, one lines up with in the block, the other one does not...likely for relief) bottom side of centre bearing and cap centre bearing location in block (note one hole for oil) thrust washer...has 010 stamped on it... I think that means it is the oversized one? One pair in block. Located on the centre bearing centre bearing centre bearing centre bearing centre bearing thrust washer thrust washer thrust washer
What is the thrust washer?
I see it on diagrams near the center of the crankshaft -- is it made of bearing material?
I am accustomed to other engines, where one of the crank shaft bearings has a collar that folds around the side -- is it anything like that?
I have my pistons/rods out but the the crank is still in the block so I don't know what those bearings are like.
What is the thrust washer?
I see it on diagrams near the center of the crankshaft -- is it made of bearing material?
I am accustomed to other engines, where one of the crank shaft bearings has a collar that folds around the side -- is it anything like that?
I have my pistons/rods out but the the crank is still in the block so I don't know what those bearings are like.
Thank you again for the pictures.
yes, it is like a collar but it isn't affixed with the central bearing.. There are groves for it to sit in in the cylinder block
Best I can tell is that it locates the crankshaft (you can see where it contacts the centre of the crank in the attached picture)...probably control the amount of runout the crank has
As for material, I don't think it is made of bearing material. It feels harder than that and it doesn't look like it has a coating on it. But I am not !00% sure
my main bearings looked better than the big end ones...but I did find some sludge lodged in the oil passages under the main bearings... why do you have to rebuild yours?
I am slightly confused (as usual) if this is for one or set of bearings
this is for a single yellow grade main bearing (not centre main bearing). You'd need 6 of these (if your engine happens to have all-yellow grade main bearings...it might not...check the stamping on the crank...if it does, you're in luck!) and one main centre bearing (whichever grading)...pretty expensive eh?
Btw I still haven't found most of the parts yet... I am working on that, I will update once I have something
Last edited by someguywithajag; Sep 5, 2024 at 03:55 AM.
My rebuild is due to several bad steps starting with broken motor mounts and letting it sit too long and forgot I had tap water in radiator so probably froze and created pathways for moisture in cylinders and then a corroded ecu connector and it was locked up by the time I got that replaced.
Don’t shun me guys— I am repenting.
Everyone wants me to junk it but I can’t. I have the original dealer window sticker and it was sold originally here in Memphis (after a boat ride from Coventry) and it’s always been in this area.
Last edited by smartobject; Sep 5, 2024 at 10:28 AM.
My rebuild is due to several bad steps starting with broken motor mounts and letting it sit too long and forgot I had tap water in radiator so probably froze and created pathways for moisture in cylinders and then a corroded ecu connector and it was locked up by the time I got that replaced.
Don’t shun me guys— I am repenting.
Everyone wants me to junk it but I can’t. I have the original dealer window sticker and it was sold originally here in Memphis (after a boat ride from Coventry) and it’s always been in this area.
Sorry to hear that. Happens. Wouldn't it be easier to replace the engine? That way you can still save the car?
You probably have a leak in the sunroof drain if the ECU corroded
The 3.2L used by Aston Martin DB7 is a modified AJ6 engine. The only parts that are the same as the AJ16 are the crank and everything that goes on it (i.e the bearings are the same except AM uses numbers to grade their bearings vs Jaguar's colour grades but I have no idea how they match up). Except for the connecting rods, which are the same as the ones in the Jaguar 3.2 AJ6.
The pistons are Aston Martin's own (I assume the piston rings are also unique to the AM but not certain). Even if the pistons were the same as Jaguar's 3.2 AJ6, they would not fit the 4.0 AJ6/AJ16
The diagrams show the parts and their numbers
To answer my own question. The way the Aston Martin grades are related to Jaguar colours is via the attached document. Size = Grade (Aston Martin speak) = colours (Jaguar speak) I got this directly from an Aston Martin supplier (Nicholas Mee) who got it from Aston Martin themselves. This is also part of the document I linked from Terry's Jag but having Aston Martin confirm it helps
These are for the V12 DB7. Apart from maybe the bottom half of the main centre bearing (can't say for sure because they are not graded), the rest will not fit the AJ6/AJ16 engine
Last edited by someguywithajag; Sep 19, 2024 at 05:42 AM.
I am rebuilding now, too. Is there any parts interchange opportunities from the AJ6 / XJ40 ?
Can we search and match piston rings by diameter?
I also need a couple of intake valve guides.
Dimensions to help with the search along with the ring profiles
Bore size is 91 mm (note piston size varies very slightly depending on the "grade" of piston you have. I have 'G' ones so the size on mine is btw 90.980 mm to 90.989 mm. Which is too small to be concerned with when it comes to sizing rings)
First compression ring face width: 1.46 mm
First compression ring radial wall: 3.36 mm
First compression ring groove depth 3.88 mm
First compression ring groove width 1.499 mm
Second compression ring. Everything is the same as first except for radial wall. Which is 3.63 mm
Second compression ring groove depth 4.42 mm
Second compression ring groove width 1.499 mm
Oil ring face width: 2.89 mm
Oil ring radial wall: 3.56 mm
Oil ring groove depth on piston: 3.71 to 3.96 mm (groove depth is hard to measure on the oil ring, so I took measurements from both edges)
Oil ring groove width 2.896 mm
Oil ring is a 3 piece set
oil ring second compression ring (note the sliced edge) top compression ring (note the chamfered edge)
OMG thank you so much.
I know it can be hard to take and upload pictures but this is so valuable.
you are welcome
and as a note to anyone else going down this path--no these are not the same size as the ones in the Aston Martin DB7. The measurements for those are attached DB7 piston rings
I managed to get piston rings from Grant Piston Rings (https://www.grantpistonrings.com/). The top and the oil rings are a match. Profile for profile. Not sure about the material. The piston rings I took off the engine are shiny while the ones from Grant are dark. The Grant ones are cast iron with a phosphate coating. No idea what the OEMs are
The second compression ring is not a match for the profile. Does this matter?
Grant piston rings product numbers second compression ring oil rings old vs new top compression ring second compression ring second compression ring new (bottom) vs old (top) second compression ring new (bottom) vs old (top)
Dimensions to help with the search along with the ring profiles
Bore size is 91 mm (note piston size varies very slightly depending on the "grade" of piston you have. I have 'G' ones so the size on mine is btw 90.980 mm to 90.989 mm. Which is too small to be concerned with when it comes to sizing rings)
First compression ring face width: 1.46 mm
First compression ring radial wall: 3.36 mm
First compression ring groove depth 3.88 mm
First compression ring groove width 1.499 mm
Second compression ring. Everything is the same as first except for radial wall. Which is 3.63 mm
Second compression ring groove depth 4.42 mm
Second compression ring groove width 1.499 mm
Oil ring face width: 2.89 mm
Oil ring radial wall: 3.56 mm
Oil ring groove depth on piston: 3.71 to 3.96 mm (groove depth is hard to measure on the oil ring, so I took measurements from both edges)
Oil ring groove width 2.896 mm
Oil ring is a 3 piece set
oil ring
second compression ring (note the sliced edge)
top compression ring (note the chamfered edge)
Update on the rings. The oil ones were of incorrect size. I replaced them with another size. See attached picture
Also a note about the dimensions--The oil ring width is 3.00 mm NOT2.896 mm
The top two rings that came on the pistons from the factory are chrome-plated. Oil rings are not (these seem to be standard across many applications)
After talking to engine builders, the consensus is that it doesn't matter if the piston rings are cast iron or chrome plated. In fact, the cast iron rings will bed in quicker. I am not putting in new cylinder liners so there's little sense in wearing the bore with chrome rings (maybe if I were putting in liners, I would reconsider). In any case, Grant piston rings will sell you chrome-plated ones as well
As far as the ring profile is concerned, the engine builders were not sure but said that it shouldn't be too much of a problem. Grant themselves said this:
"Most of the 1.5mm compression rings for Jaguar applications either call for Chrome top with Torsional Twist second groove ring or both Cast Iron torsional twist compression rings. I sent you both cast iron compression rings because we do not have any chrome plated available at the moment. You’ll have no problem at all using the rings I sent you."
As further education, this video explains the differences as well:
