PLEASE HELP!!!! Hilux ln106r compression issue

[StarSteele]

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. 

Thanks!

[ozieagle]

Hi Joel,

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

 

Herb

[CONROD]

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 May 16, 2023 by CONROD

[StarSteele]

Thank you guys! ill be taking it for a drive tomorrow, let you know how it goes and ill to a compression test

[StarSteele]

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. 

[CONROD]

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

[StarSteele]

Exhaust and intake valves were all lapped. and valve clearances were good

[CONROD]

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

[StarSteele]

Thats a good point, ill give that a go, thanks. If that doesn't work, do i Just take it to a mechanic?

[antiussentiment]

Reading this left me in the boat with the "have you checked the valves" suggestion.

Even if the rings were not bedding in well, I'd still expect some measurable compression even if it was a bit low. Maybe you have a valve that's sticking / has a bent stem? If you put a credit card over the exhaust when it's idling does it flap back and forwards like the exhaust is sucking as well as blowing?

Have you ruled out a cracked head or leaky head gasket? Are there bubbles in your coolant when the engine runs etc?

[StarSteele]

So i have now checked the coolant, no bubbling. the exhaust, only blowing, there is no suck and blow. cracked head and leaky gasket is ruled out after i have sprayed soapy water around and no bubbles. after running the engine again i do think that it is a valve issue as there is fuel vapour coming back out the intake manifold. i don't understand how though because my timing is lined up. its an interference engine so if it wasn't aligned, if have pistons hitting valves, right? and the valves have been lapped and also don't seem bent. I might take it into a shop and get a compression and leak down test just done so i can get the best readings and find out for sure where my leak is coming from