Rebuilt motor has no compression

[Driftit 2018]

Recently purchased a running M20B20 that had a blowen head gasket. The car was still running and started first shot every time.

I purchased a second hand head from a car that was running fine. Idea being I would just get a Head set and put the new head on and go.

It took me a while to blast all the caramel source out of the block due to oil and water mixing.

Once clean I put the new head on. Plugged everything back in and set timing etc..

But she would not start. So I checked Spark, Fuel, Airflow meter, plugs, Timing marks (twice). Everything was fine. Relalised it was turning over far too freely.

A compression check found that she has near none. Ranging from 50PSI to 90PSI over all 6 cyls.

I have checked the lifter gaps which seem to be fine.

Why else would there be a lack of compression over all 6 cyls?? Just seems odd that it is all of them.

[Jamez 2147483647]

warped block/head? i have the problem of too much compression on my m20b20 getting 200psi across all 6

[topcat 11]

maybe a cheap one, but are the spark plugs done up?

caught myself out on that one

[Graham m5 0]

Again may be a bit of a mad one but you did fit the headgasket correctly and not the wrong way round

[BM WORLD 1275]

camshaft timing out by a few teeth

[Driftit 2018]

I am putting it down to ether the head gasket incorrectly fitted. Although I am sure I did this correctly following the marks on the gasket or there is a problem with head itself (warped etc...)

Timing is correct. We first thought I could be a couple of teeth off. But this was not the case.

Plugs have been in and out a few times now.

[QuickSilver 0]

I have once incorrectly torqued up a head which gave crazy results. Did all the head bolts go down in order, and with correct settings?

[Driftit 2018]

Yes the head was bolted down in the correct order. With the three steps. Tourqe, 90deg, 90deg. etc..

[R90S 2]

I suspect that you may have the cam timing 180 degrees out. It's surprisingly easy to do. . . .

There's a simple check to see if the cam timing is close or not: turn the engine over until the piston in #1 cylinder is at TDC. The valves on either #1 or #6 should be "rocking" i.e. the exhaust valve just closing and the inlet valve just opening. If that's not happening, the cam timing is wrong.

The next thing to check is that the valves are actually closing fully.

If the cam timing is close, and the valves are fully closing, then you can start looking at the weird options like the headgasket.

hope this helps

[Driftit 2018]

Yeah we checked this on Sunday. But the timing is all correct. And the valves are closing.

At first I thought it could have been because the rockers were too tight. But they have the correct amount of play as I tested it with a feeler gauge.

Going to yank the head off and have a look under there. Doesn't take long on a facelift. Nice and easy plugs. Not like the PFL motors.

[*Glenn* 854]

I suspect that you may have the cam timing 180 degrees out. It's surprisingly easy to do. . . .

There's a simple check to see if the cam timing is close or not: turn the engine over until the piston in #1 cylinder is at TDC. The valves on either #1 or #6 should be "rocking" i.e. the exhaust valve just closing and the inlet valve just opening. If that's not happening, the cam timing is wrong.

The next thing to check is that the valves are actually closing fully.

If the cam timing is close, and the valves are fully closing, then you can start looking at the weird options like the headgasket.

hope this helps

I'm sure you are spot on... I was thinking the same and told Dan to take the rocker cover off so I could go and have a look...I'm still waiting for a phone call ?

[Driftit 2018]

I'm sure you are spot on... I was thinking the same and told Dan to take the rocker cover off so I could go and have a look...I'm still waiting for a phone call ?

Sorry Glenn. I seem to always be busy when you are not and vice versa. I did check the rockers though. Will still get you to come have a look at some stage.

[CamB 48]

As unlikely a problem as it might seem, you should also check that TDC really is TDC (if the head is still on, carefully stick a screwdriver (etc) down a plug hole and feel for when it reaches TDC - it won't be super precise but will be within a degree).

Then check the cam is correctly aligned.

[*Glenn* 854]

As unlikely a problem as it might seem, you should also check that TDC really is TDC (if the head is still on, carefully stick a screwdriver (etc) down a plug hole and feel for when it reaches TDC - it won't be super precise but will be within a degree).

Then check the cam is correctly aligned.

Thats what I was also going to check for Dan as well. I'm more concerned that the front pulley is actually in faze. TDC may not be TDC on the pulley. If valve clearances are still Ok no damage may have resulted in trying to start the engine. This car was running when I sold it to Dan, appart from the headgasket/ head problem that we all new about. So hopefully there is only something minor wrong.

Edited March 3, 2009 by *Glenn*

[Driftit 2018]

Motor was definatly at TDC when I put the head back on. Head was set to correct markings and Valves fully closed (rockers had play) when I mated the head to the block. Turned the motor over by hand first to make sure that it didn't catch etc.. And marks line up every time. Have even made sure the rotor was aligned with the point for number 1 piston to get spark just in case that was out somehow.

It must be a head gasket problem. Maybe even though I was reading the markings for it I ended up still putting it in upside down? Is that even possible with the dowls? And would it cause this problem?

One more thing. When the motor was being cleaned out quite a bit of water filled up the bores. We made sure they were drained out though. Is it possible that the rings have rusted up or something?