Low compression to all cylinders after rebuild

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Tzortz

New Member
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5
Location
Greece
Hi,
just rebuilt my 1999, 1.8 petrol Freelander (head gasket issue).
Engine won't start after the rebuild. Here's a brief list to what I did:

- Skimmed the cylinder block (sent it to a machine shop).
- Installed NEW cylinder head (brand is TopLine).
- Installed new: valves (plus springs and caps), MLS gasket, reinforced head screws, water pump, thermostat, belts etc etc.
- Did the screw patterns/torques by the manual.
- Timed the cam belt and tensed it (it's still timed).

- Note: I didn't lap my new valves on the new head because the guy from the shop told me I don't need to, since both head and valves are new.

After failing to start the engine:
- I did a pressure test. Readings on cylinders 1-2-3-4 were very low, 30-25-25-30 psi (about 2 bars).
- I checked my pressure test kit on my other car, it read 175psi (12 bar) to all 4 cylinders, so those 25psi readings seem correct.
- Checked the timing belt, camshaft gears, crankshaft gear. Everything looked totally fine, all gears aligned to their marks.

Any help is appreciated.

2021-08-28 15.21.55.jpg
 
Hydraulic tappets sticking/not operating correctly?

Iirc back in the day the K were famous for sticky tappets, cure was 1/2 pint of diesel in the oil then run it until engine quiet, then oil and filter change.
 
As above Tappets hydrauliced out. Have they had chance to refill with oil yet ?
Timing out 180 ? U said checked marks etc but maybe worth refitting it from start
Always lapped valves in new all round especially as you don't know wether seats and valves are machined to match to start with

Had block machined and new head
What about pistons n rings ? Ring gaps offset ? Is some fitted assumedly? Sorry daft question but have had recon bottom ends from Volkswagen in past at dealers and not found out they hadn't fitted rings until it was all in and not starting

Do you have access to an air line maybe pressure up the cylinders see if there's any signs where the airs going ??
 
Last edited:
Turn it over with the starter, plugs removed, to get oil to the tappets.
All tappets stuck seems unlucky, check timing though.
After timing did you turn it over it by hand a couple of revolutions to check?
 
Dont you have to prime the tappets by hand in a bucket of oil or am I imagining that?
 
Presumably the cam pulleys are located on the correct pins for the cam they're driving?

It's unlikely to be the tappets IMO, as there's under 1mm of tappet stroke, so even if they were empty of oil, the valves would still open 8mm, which is enough start the engine.
 
lynall said:
Dont you have to prime the tappets by hand in a bucket of oil or am I imagining that?
Click to expand...
You should bleed the air out of the tappets see pics of Honda special tool for that very purpose, like you say submerge the tool with the tappet inside in oil & have a good pump until all the air is expelled. It was to stop it sounding like a bag of nails on start up from a rebuild. Unbled tappets wouldn't cause low compression. I would NEVER not lap valves in even if the head/valves were new, they should only need a quick lap with fine paste but always fill the ports afterwards with petrol to check for leaks. Have to agree always turn engine over by hand to make sure nothing's hitting & full throttle when doing a compression test. Like Nodge says ax the compression is evenly low on all cyls. it's unlikely to be all the unlapped valves more like a timing issue.
20210829_142228.jpg
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20210829_142258.jpg
 
Gentlemen, thank you all for your valuable info.

Fl@pper, I didn't touch pistons and rings, as they worked fine before. The only thing I did to the block, was skimming it. I'll try air-pressuring the cylinders to check them.

Andy Warren, it was my stupid mistake not lapping my valves and not using petrol to check for leaks. Was in a hurry (and lazy), now learned my lesson :(

As for the timing, I turned the engine over by hand 4-5 cycles and the timing marks looked perfect. They still look perfect now, after many turnovers.
Also, kept full throttle during compression tests.

So, most probably it's a stuck tappet (I really hope it is!).
I didn't condition them in oil or anything, didn't know I had to.

I'll also recheck the timing and I'll post an update here.
 
freelance said:
Or did they skim the block with the liners in?
Click to expand...
They skimmed the block with the liners in.
I didn't remove the pistons at all.
Today I poured about 5ml of oil into every cylinder (from the spark plug hole). I'll retest tomorrow for compression to see if anything changed.
 
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