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PLEASE HELP!!!! Hilux ln106r compression issue


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Hello I have a 1989 Toyota Hilux ln106r. the engine has been swapped to the slightly larger 3ltr 5L engine from the 2.8ltr 3L. 

The engine is Mechanical fuel injection and non-turbo


I recently conducted a partial rebuild as my timing belt needed replacing, the engine was smoking a bit and there were some oil leaks.

Here's what I did on the rebuild:

Engine fully pulled apart and cleaned

Cylinder bore measured and were almost completely stock

Cylinders were honed and piston rings replaced with Chromoly rings

Full gasket replacement

New timing belt, tensioner and Idle pulley

New water pump


The engine went back together and after starting her up, I had a rough idle and some minor fuel issues. 

Ordered New injectors, put them in and double checked the timing


Again, Started it up and same issue.

We realized there was a Misfire and after conducting a compression test, found that cylinder 4 (furthest cylinder from front of engine) had zero compression, and all the other cylinders were low


I decided to take apart the engine again.

I rechecked the compression ring gap spacings and found that they were almost inline with each other so I respaced them with more care the second time around.

I then lapped the valves and replaced the valve oil seals, and the valves seated well.

Replaced the head gasket again, and put the engine back together, triple checking timing, torque settings etc.


Started her up again today with some hope, but no change. Engine still idles rough, and I can hear it misfire every now and then.

I have no idea if there is any other possible issue unless there is something seriously wrong with this engine. 

I am not giving up on this engine, I have to find out what is wrong with it, even If I cannot repair it.  I will conduct another compression test soon but figured I would put up a post on a forum for any input which would be so very much appreciated. 


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Hi Joel,

You may just need for the engine to run in some more.  Bedding rings in needs hard acceleration.



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Posted (edited)

Low rpm, low speed, say 30-40kph, 3rd gear. Then wide-open throttle, do this half a dozen times, it forces the Top Ring out, to bed in, but don't rev the sh+t out of it, slow down and repeat process, but to have Nil compression on one cyl points to something not right, and having associated miss


Head tightening procedure and torque specs:

  • Step 1: 78 Nm; 8.0 kg·m; 58 ft·lb
  • Step 2: Turn all bolts 90°
  • Step 3: Turn all bolts 90°

Camshaft bearing cap

  • 25 Nm; 2.5 kg·m; 18 ft·l
  • Cylinder block
    Cylinder block alloy Cast iron
    Compression ratio: 22.2:1
    Cylinder bore: 96.0 mm (3.78 in)
    Piston stroke: 96.0 mm (3.78 in)
    Number of piston rings (compression / oil): 2 / 1
    Number of main bearings: 5
    Cylinder bore inner diameter: 96.000-96.010 mm (3.7795-3.7799 in)
    Piston skirt diameter 95.940-95.950 mm (3.7772-3.7776 in)
    Piston ring groove clearance: First 0.028-0.077 mm (0.0011-0.0030 in)
    Second 0.060-0.105 mm (0.0024-0.0041 in)
    Oil 0.030-0.070 mm (0.0012-0.0028 in)
    Piston ring end gap: First 0.350-0.470 mm (0.0138-0.0185 in)
    Second 0.400-0.500 mm (0.0157-0.0197 in)
    Oil 0.200-0.500 mm (0.0079-0.0197 in)
    Piston pin outer diameter 29.000-29.012 mm (1.1417-1.1422 in)
    Connecting rod small end diameter (standard) 29.008-29.020 mm (1.142-1.1425 in)
    Crankshaft main journal diameter: 61.985-62.000 mm (2.4403-2.4409 in)
    Crankpin diameter: 52.988-53.000 mm (2.0861-2.0866 in)
Edited by CONROD
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  • 2 weeks later...

Update, we have taken the Hilux for a drive out on some hills behind our house as, ranging the revs, gears and load. there was no change, engine still misfires, low power etc. Did a compression test today, still no good. front three cylinders are all good, (about 300psi when it cranks) back cylinder still has 000 compression. I have no idea what the issue could be, i have worked on the engine for hours and i simply don't understand. 

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Valve clearance been checked and double checked, Exhaust valve not burnt?

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Have you tried putting a couple good squirts of engine oil into the Cyl to see if that builds up compression?

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