Replace head gasket, compression test

ng_randolph said:
I am guessing that is from Service Letter 100-18, dated 12-10-81? I found a copy here.

It is interesting that the procedure for the Pre-Delivery Inspection (PDI) calls for turning first 60°, then 30° for a total of 90°, while the torque procedure after the head has been removed and reinstalled is torque to 14.5 fl-lb, then to 29 ft-lb, followed by turning 90°, followed by another 90° for a total of 180°.

Perhaps the PDI torque requirement is to correct for incorrect torquing at the factory?
Click to expand...

I would 'guess' that this extra 90 degrees is in ADDITION to the original torque and angle original manufacturing torque procedure ... the engine would have heat cycled a few times during delivery (on and off the boat, on and off the truck trailer etc) so the additional 90 degrees is a retorque after heat cycling the gasket.

SteveC
 
Thanks for digging out the bulletin.

As you mentioned, it's logical to conclude that the additional 60 + 30 during the PDI is there to correct an assembly problem at the factory, especially when compared to the procedure used for reinstallation of the head after repair.
 
Could be, but they don't mention it as a corrective action, which would imply it was SOP for all 17mm versions.

Since the standard guide for head install doesn't mention any retorque, one may assume there is none, however the old setup doesn't mention a retorque requirement either, and that is SOP.

I'm going to lean toward the assumption (as Steve pointed out) that is to compensate for gasket settling/compression after heat cycling, as with the standard bolt. Chris O described this as the appropriate procedure, and he has experience from Fiat NA.

Worst case, I snap a bolt due to overtorquing & have to redo the gasket again. :sigh:
 
Rupunzell said:
Reverting back to the original Lampredi design specifications and parameters made more sense along with using the highest quality studs and re-torquing early on in the engine's run time. What is important is proper clamp force uniformity on the cylinder head to block interface. If this can be assured by re-torque and high quality stud/washers/nuts there is little reason to avoid this proven practice.
Bernice
Click to expand...

I feel like ignoring this will subject me to Murphy's Law - so, Bernice do you have a catalog of specific hardware ( ARP? studs, hardened washers, etc.,) that will work for the later block with the 10mm threads (edit: they are all 12mm regardless of style? - Never actually measured one) If I'm going to investigate this as an option, I'd prefer to go with what has been tried and tested vs. shooting in the dark.

Thank you
 
Found the answer I think

After a bunch of digging, I found true TTY replacement headbolts for the later Fiat head with M10 bolts. (The first set I had ordered online somewhere do NOT look like TTY, they have no necking of reduced diameter anywhere).
These are made by Elring.
The instructions for the bolts answer the question about the retorque.



29 ft/lbs
90°
90°
run for 1000km
retorque 60°-90°

This matches the service bulletin.

Interestingly, there is a variant without retorque also (in the third collumn) that goes

15 ft/lbs
30 ft/lbs
90°
90°
without retorque

Strange.
So when in doubt, the ARP hardware is a good option too.
I just liked the idea of TTY after reading up on it.
I feel that it is discussed here in a negative way that is undeserved.
I do think that it is a complicated subject because, as described, it is a SYSTEM and we cannot buy a gasket and bolts as a matched kit so there is always the uncertainty that parts might not match.
 
Elring

Hey Ulix,

good find. And you can still get the Elring head gaskets to suit, e.g.:

10 bolt / 144.190

14 Bolt / 144.210

Cheers,
Dom.

Ulix said:
After a bunch of digging, I found true TTY replacement headbolts for the later Fiat head with M10 bolts. (The first set I had ordered online somewhere do NOT look like TTY, they have no necking of reduced diameter anywhere).
These are made by Elring.
The instructions for the bolts answer the question about the retorque.



29 ft/lbs
90°
90°
run for 1000km
retorque 60°-90°

This matches the service bulletin.
Click to expand...
 
Last edited:
Nice find Ulix. Thank you for your input!

That chart does match the retorque procedure which is satisfying as confirmation of process.

Did you take any pics of the two version bolts you purchased?

Do you have the part number and source for the TTY bolts you purchased?
 
How about for a possible explanation of the two different torque and angle procedures...

one procedure ( the one without retorque after 1000km) is to suit a polymer composite style gasket (Astadur), and the second procedure which includes a retorque after 1000km is for regular composite construction gaskets... this make sense to me as for different engine both styles of gasket were available thru Fiat.

Ulix the Elring bolts, are they 17mm head or 15mm?

Hussein, Elring make very good products so a combination of Elring gaskets and bolts would be a quality solution.

SteveC
 
Yes - I did a quick search on eBay UK for elring , fiat ritmo bolt kit & came up with that number - I ordered a set from Latvia. See what they look like when they get here.
 
Yes

Yes, 760.870 is the Elring part number.
Dirt cheap on ebay! I paid twice that from a Fiat specialist who found them for me and who supplied the data sheet which does not come with the bolts.
Steve, the ebay ad lists the head size as 15mm. Good point as I have been shopping for a 17mm offset head bolt wrench! :tomato:

I'll try to remember to take some pics.
At first glance the bolts don't look like other TTY bolts which have a pronounced neck.
On closer inspection, it is evident that the whole unthreaded shaft section is a slightly smaller diameter than the threaded portion.
I compared to the other no-name head bolts I had bought and the difference is visible.
This ensures that the unthreaded shaft is the "weaker" part and will stretch rather than the threaded part which would/could damage the threads in the block.
 
Precisely.

If Torque To Yield screws are used, it must be in the context of a system, elements must be of known specification. This Elring package appears to be a good system as Elring is well known for quality OEM gaskets and industrial sealing systems.


TTY system has not been good to Saab, Years ago when Saab used TTY cylinder head system, Saab experienced a LOT of head gasket failures due to TTY scows loosing their clamp load. Service notes were issues to re-torque TTY by loosening about 1/2-1 turn then torque up to 45ft/lb then another 90 degrees. Beyond this Saab had several re-designs of the TTY cylinder head screws. Under head design changed, washers changed, fastener finish changed and the shank changed..

http://www.swedecar.com/images/photos/Head bolts.jpg

The TTY concept is based in good technical rational and material science fact, applying this into real world product and production is, as with many things more complex than expected.


Bernice


Ulix said:
After a bunch of digging, I found true TTY replacement headbolts for the later Fiat head with M10 bolts. (The first set I had ordered online somewhere do NOT look like TTY, they have no necking of reduced diameter anywhere).
These are made by Elring.
The instructions for the bolts answer the question about the retorque.



29 ft/lbs
90°
90°
run for 1000km
retorque 60°-90°

This matches the service bulletin.

Interestingly, there is a variant without retorque also (in the third collumn) that goes

15 ft/lbs
30 ft/lbs
90°
90°
without retorque

Strange.
So when in doubt, the ARP hardware is a good option too.
I just liked the idea of TTY after reading up on it.
I feel that it is discussed here in a negative way that is undeserved.
I do think that it is a complicated subject because, as described, it is a SYSTEM and we cannot buy a gasket and bolts as a matched kit so there is always the uncertainty that parts might not match.
Click to expand...
 
Revisiting the ARP stud thread Steve referenced - it's locked so I can't post in it - Rob shows one of the aircraft wrenches used in place of the Fiat tools:

Screen%20Shot%202016-10-02%20at%209.04.25%20PM_zpsdjp7nuud.png


The question is, there are two Fiat tools required, due to the variation in clearance. Does this ONE tool actually fit all five of the rear side bolt heads?

I'm going to have to either make another pair of 15mm tools to replace the 17mm set I made here, or buy another tool to mod...
 
Aircraft Spruce wrench for ARP 12 point nuts

Hi Hussein,

That Aircraft Spruce wrench fits the ARP 12 point nuts I am using.



I may need to remove the carbs and manifold to retorque the nuts on that side of the head, but since I am using the water jacket holes for the fitting of manifold aligning pins, that won't be much of an issue. i.e. I don't have to worry about leaking coolant when I remove the inlet manifold.

Cheers,

Rob
 
rjplenter said:
Hi Hussein,

That Aircraft Spruce wrench fits the ARP 12 point nuts I am using.



I may need to remove the carbs and manifold to retorque the nuts on that side of the head, but since I am using the water jacket holes for the fitting of manifold aligning pins, that won't be much of an issue. i.e. I don't have to worry about leaking coolant when I remove the inlet manifold.

Cheers,

Rob
Click to expand...

Thanks Rob. I would be modding the wrench end. For the sake of others looking at the tool - does it fit the two end bolts?

8EE12BB7-549D-4345-BBCE-9001AABA0A10_zpsafjsamud.jpg


5280B605-6DFB-4D72-9AEF-9D34F42675C0_zpserlkz71z.jpg
 
I have a German factory service manual for the Regata (this is the sedan version of the Ritmo / Strada) printed in 1983. Most of the Regata engines are from the same family of SOHC engines as the ones used in the X1/9. The Regata FSM lists 138.B2.000 and 138.B3.000, among others.

In the section about the cylinder head it states that "...the cylinder head gasket is of the ASTADUR type. The particular composition of this head gasket causes it to polymerize during use". It also says "When using ASTADUR head gaskets, it is no longer necessary to re-torque the head bolts after 1000 - 1500 km".

There are also a few precautions about the ASTADUR head gaskets:

- Keep the gasket in the sealed packaging until just before use.
- Do not oil or grease the gasket. Keep the mating surfaces perfectly clean.
 
So I am installing my head for the first time this week or weekend. I just wanted to say this thread was a fantastic help. If there was a way we could flag this thread or save it in some way for easy searching and access that would be a great benefit to everyone doing their first head gaskets. While the title is "Replace Head Gasket Compression Test" is close, it doesn't quite show how helpful the 4 pages really are.

PS. I wrote this post so i can find it in the next 48 hours to install my own head. Completely personal gain. :D
 
AKimball92 said:
Completely personal gain.
Click to expand...
But seeing your current post allowed me to view the thread. I had not come across it previously (this occurred during my brief absence from the forum), and agree it is very informative...along with the several included links to more good info. So you provided me the gain as well (I'll be pulling the head off mine eventually). Thanks for posting to revive the old thread!

I realize it isn't very practical to actually do, but wouldn't it be nice to extract all of the excellent info from these wonderful threads (e.g. all of the "Wiki best of" stuff and a tons of others throughout the Xweb history) and compile a book. Something like has been done by the owner's clubs for Porsche's and BMW's and MB's. The gold-standard of Fiat X1/9 handbooks.
 
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