Technical 2018 QUBO PETROL - CYLINDER HEAD BOLT TIGHTENING PROCEDURE

[QuboPete]

Hi Folks

I'm an oldie used to working on my cars from the pages of oil spattered Haynes manuals, so this is quite a new experience for me!

I have a 2018 1360 petrol Qubo with a failed head gasket. I have the head off, but I'm struggling to find any information on the cylinder head bolt tightening sequence, and procedure - torque figures etc.

I'd be most grateful to anyone who can point me in the right direction. The engine is a 1360 4 cyl 8 valve with a SOHC acting directly on buckets & shims. Picture of the partly stripped engine bay to help identification of the engine type.

 

[Zardo]

Hi Folks

I'm an oldie used to working on my cars from the pages of oil spattered Haynes manuals, so this is quite a new experience for me!

I have a 2018 1360 petrol Qubo with a failed head gasket. I have the head off, but I'm struggling to find any information on the cylinder head bolt tightening sequence, and procedure - torque figures etc.

I'd be most grateful to anyone who can point me in the right direction. The engine is a 1360 4 cyl 8 valve with a SOHC acting directly on buckets & shims. Picture of the partly stripped engine bay to help identification of the engine type.

There should be a plate which shows the engine number

VEHICLE SUMMARY IDENTIFICATION AND PAINTWORK PLATE

"This is stuck on the driver's door pillar" (says the owner's manual, pages 160-161).

In addition, the engine marking should be stamped on the cylinder block and include the type and the engine serial number.

Maybe have a look there?

 

[QuboPete]

Hi Zardo

Many thanks - sorry, should have included the engine number in my post:-

350A1000
2395573

 

[Zardo]

Looks like it's either

1.4 Natural Power	350A1000
1.4 Petrol Euro 6	350A1000

Cylinder head

Screw

M9

2.9 ÷ 3.1 + 90° + 90° +/- 3°

1.4 Natural Power E5/E6 1.4 Petrol Euro 6

these are daNm, so it should be 30 Nm of torque in my opinion (no idea what the 90° are about)

there should be 2 x 5 cylinder head screws, start with the middle front screw (1)

REAR
8 - 6 - 2 - 4 - 10
cam belt cam
7 - 3 - 1 - 5 - 9
FRONT

by the way, when I changed my multiair, I used progressive torquening, like torquening all up to 10 Nm, then 20 Nm and finally to the target value whilst still doing it in the prescribed order.

EDIT: I asked ChatGPT about the degree values. I would find it useful if somebody from the Forum could verify:

The torque specification for the cylinder head screws in your Fiat technical manual combines two elements:

1. Initial Torque (in daNm):
   The value of 2.9 ÷ 3.1 daNmcorresponds to the tightening torque applied in the first step.
   • 2.9 to 3.1 daNm is equivalent to 29–31 Nm, as you've correctly interpreted.
2. Angular Tightening (in Degrees):
   The subsequent +90° + 90° ± 3° refers to two additional stepsof tightening by a specified angle:
   • After the initial torque is applied, each screw should be rotated an additional 90 degrees (quarter-turn).
   • Then, rotate it another 90 degrees in a separate pass.
   • The ±3° allows for a small margin of error when applying the angular torque.

Explanation of Degrees in Torque Specs​

Angular tightening is used to ensure consistent clamping force, which depends on bolt elongation rather than friction. This method is commonly used in critical applications like cylinder head bolts, where precise clamping is necessary.

In your case:

1. Torque all screws to 29–31 Nm.
2. Tighten each screw by 90 degrees.
3. Perform another 90-degree turn on each screw, within a tolerance of ±3°.

It's critical to follow this sequence in the proper order and pattern (usually specified in the manual) to avoid warping or uneven clamping of the cylinder head.

use information at your own risk

 

[QuboPete]

Hi Zardo

That's great - many thanks!

I usually torque up progressively as you do. The ChatGPT rider you have added about the final 90 degree tightenings accords with my understanding.

The tightening sequence looks pretty well what I would expect - generally starting in the centre and working outward.

Just ordered the new head bolts.

I need to do another post about valve clearances. I was pleasantly surprised to find solid (rather than troublesome hydraulic) lifters.

Thanks again for your time.