GregBBRD

Early S4 narrow fire ring on top gasket. (All of 1987. Not sure now "far" into the 1988 models.)
Later S4 wide fire ring on bottom gasket. (And an '87 engine would not have a wide fire ring gasket.)

My guess is that one (or both) of the heads on the engine you bought is cracked at the "usual" spot.
Someone put head gaskets in the engine (wide fire ring), thinking this was the problem. This did not fix the engine and it was removed.

ador117

Bonjour Greg,
It is what I thought… I would just prefer the scenario where the mayonnaise was made at the radiator… so they changed the head gasket for nothing…
lol
I’m familiar with the idea of the 1R heads cracking but not with where exactly they crack. I will look for this spot on the forum…
when I removed my 4 heads!!! I was very careful cracking all nuts first in order and then unscrew them in order too…

for the block I’m hesitating now… the cylinders of the spare engine block looks so great… I’m quite sure the bores will be about manufacturing tolerances…

I’ll see. Now the 2 first heads are at the shop for pressure test and skimming…

have a great day
Raphael

FredR

Raphael,

Sad to say as per my previous post it very much looks as though one of the heads in your new acquisition has failed thus communication between the cooling circuit and the engine and the consequent formation of emulsion. Doubtless GB 's analysis will be spot on.

Ownership of these cars does not get any easier with the passage of time and as for the size of the bills....?

Let's hope your original 1R heads fare better!

GregBBRD

Just a random data point, from a single source, but we see cracked '88 heads at a 5 to 1 ratio over '87 heads.

ador117

Bonjour FredR,
Yes, you are right... maintaining this car is more and more challenging... If one head is not cracked I'll be happy... as they are not corroded...

Greg,
English is not my native language... I do not understand what you would like to say...
SN of my engine is 81J01266 (M28/41 part number) and my S4 is a 1988 car.
The spare engine is 81H00423 and the PN engraved is ATR M2841. Should be an earlier engine.
So I clearly have early S4 engines, before the heads where improved...
Do you means that for 5 1R head you work on, you find 1 cracked?

I carefully inspected the areas around all the countersinks of the heads...
One head looks great. no suspect mark.
On the other one... in the center... maybe there is a crack. not sure... I will see when I will send them for pressure check... I hope pressure check is 100% accurate and that cracks do not appears only while the heads are bolted on...
Raphaël

Darklands

ATR could mean Austauschrumpf (Exchange short block).
Maybe this engine was refeshed years ago.

GregBBRD

We see more cracked '88 heads than '87 heads, by a large percentage.
Even though all the heads have the same casting number, I doubt that they were all cast at the same time.
Since all castings have a certain amount of "core shift", my guess is that the later heads tend to have more core shift and crack easier.

Since your purchased engine is an "ATR" engine, it could easily have later heads installed on it.

Look on your 4 heads. What are the casting dates? (This is cast inside a little circle, near the casting part number.)

ador117

Greg,
My original heads are at the shop for pressure check...
On the spare engine I found this:


If the dates are 85 and 86... should be old... I did not find any other numbers in a circle around the heads...

ador117

Yes, obviously the engine has been reworked: the head gaskets do not look like my 34 years old ones.
And on the bloc, all cylinder group has been stamped on the side of the original one. All stay group 1 except one that changed from group 1 to group 2:


Today I’m leaving France for one week. When I come back I will open the block to check the health of the lower part of the engine. Under the pan, so far everything looks in good shape. I did not measure it but Almost no axial play on the crankshaft.
I was worry about the mayonnaise and corrosion. It is why I open it right away. but I did no found corrosion inside the engine. The issue is more presence of deposits sometimes like gélatine and sometimes like sugar everywhere… 🤮
globally I’m satisfied. I have plenty of spare parts, in particular the cam covers, the harmonic balancer that looks great, several parts that I had to change are in good shape, the block should be good and, I hope, at least one head…
I should be able to maintain the engine for the next decade…
I found some differences compared with my engine.
have all a great Sunday,
Raphael

ador117

Bonjour,
Heads have been pressure tested good and skimmed. Only 0,1mm removed and the heads were at the high side of the tolerance... So now I'm nominal!!! If the bloc kiss is light enough, I should be able to stay with the stock head gasket (1.1mm)!


Progressing...
I found someone to kiss the blocs... The bloc of my car just need a French kiss!!! There is just the mark on the cylinders to wipe out. For the spare block, I want a correct oil chimney surrounding surface so it could be a more insistent kiss I think!!!
It will be the next step!!!
Today I measured the weight of the rods has I may balance the crankshaft. The flywheel has been surfaced but he has suffered in service... After skimming it remain cracks and the machinist found it twisted... So I'm not sure it is still balanced after skimming... Tomorrow maybe I will find someone to check that.
I was very surprised to measure the exact same weight to all rods... 845g : no dispersion between all 8 rods... For the pistons, I have 6 grams dispersion... I still not have cleaned them but no matter, weight dispersion on the pistons will be higher. I will reduce this dispersion.
I also check the gap between the rings and the grooves on the piston. The ring 2 is well within spec. However, the upper ring is at the wear limit on almost all the rings. I don't have the new rings yet but the oversized piston thickness of the upper ring looks to be greater because the gap is much better with it... Rings looks to be worn out not only on the diameter but also on the thickness... No doubt that rings needs to be changed!
Have all a great weekend.
Raphaël

GregBBRD

Beautiful!

ador117

Awesome !!!
I found THE guy!!!
He has at least 20 different machines… they are only 2 machinists!!! Incredible!
He is familiar with Alusil : he has a former Sunnen machine that his father used to work on and he bought a recent one that does the job automatically !!!
He has big machines to skim big boat engines… and everything to correctly revise valves stuff!!!
And balancing of the crankshaft and all stuff attached to it!!!
He already have the crankshaft ! I will bring him back the blocks and my 2 heads, springs and valves!!!
Big step today !
Cheers,
Raphael

GregBBRD

I thought you were traveling....

ador117

I come back from Washington already… going to Florida in November for one week and again in December for 2 weeks…
Today I’m in the center of France for a track day (with the spare car… my 406 V6…)… not a car designed for that but It is all I have for the moment !!! Working great so far! Maybe another engine to rework soon…
So yes I’m traveling back and forth!!!
But in between… or during my travels… I try to progress on the 928 project! On the travel today I also bring the exhaust manifolds for ceramic coating…
Looking forward turning the key again!!!
Good evening Greg

ador117

Bonjour,
Today I disassembled the spare engine :
- the crankshaft is 1st size reconditioned,
- all bores and pistons are... oversized!!! I was looking for one oversize piston... now I have 9!!!!!! I has been inspired not to buy an extra one!!! I will have plenty of life on my blocs!!!
- I have a significant stain in one bore : deposit or corrosion. It is in the lower part of the bore, on the side. looks to the the consequence of the deposit found on the side of one piston (see below). I think after honing/lapping it will be good.
- all the pistons are not drilled!!! I don't remember when these pistons not drilled appears? They have more carbon deposit than the ones of my other engine... Almost all have a strange deposit on the side it looks like oil deposit and aluminum corrosion... I will clean that.

- piston rings looks in very good condition. On the top of the upper one, the black deposit is still partially present and the end gap when I place it in the bore is within spec (0,37mm). There were plenty of carbon behind it in the groove, mine has no carbon there. There is a kind of lip on the inner side of the ring. The oil scrapper is a 3 pieces one.
This looks to confirm that the engine has been reworked latter after the donor car was produced and the engine failed (mayonnaise) few miles after rework. Tomorrow I will measure the bores with a micrometer but I think they will be not worn at all. I feel nothing on the bore with my finger... no slight step... event on the lower end of the bore as on my other bloc.

On this bloc, there is an oil valve that is missing :

I did not find any change in the service manuals about that from 1987 to 1988... Someone knows what is this change?
- finally, I remarked these 5 points stacked on the lower part of the rod of cylinder 8 (no mark on the others) :

Someone knows what it means? That the crankshaft has been reconditioned?
Have a great evening,
Raphael