Clacking/tapping noise due to blown head gasket

[wotan2525]

I believe you can set the distributor while the crank is at TDC -- there is not enough teeth on distributor to get it as finely tuned as you are expecting based just on the install. Set the motor at TDC, install the distributor with the rotor pointed at the #1 wire and it should run. You will still have to "time" it to the correct specs.

[roosm]

Hmm.. From what I have read I want 10 cam / rotor degrees BTDC not 10 balancer degrees. The balacer degrees on the tape, as I understand it, are actually not 10 degrees rotation of the balancer but 10 degrees rotation of the cam and 20 degrees of the balacer.
10 degrees at the balancer would be 5 degrees BTDC for the cam / rotor...

My balancer has chipped paint for the 2 inches around the TDC machined marking. Any paint/tape or other on the balancer would be invisible.

Any one know for sure if it is 10 BTDC cam/rotor/balancer?

[ssa]

I've never heard anyone refer to timing as degrees of cam or rotor rotation. Its always expressed in degrees of crankshaft/balancer rotation. The cam turns half the rpm of the crank so there's no reason to reference cam degrees of timing all that's important is how many degrees before the crank hits TDC do you light the plug. Too late you lose power and too early you try and drive the crank out of the bottom of the motor.

[roosm]

Hi!

Yeah, I googled some more yesterday and found procedures for how to measure where to put the mark and they referred to it as being balancer degrees.
8 inch balancer diameter * PI (3.14) / 36 (360 degrees * 10) = 0.872 inch before TDC. So that should so it. Well, if the balancer is 8 inch...

Don't know where I found someone referring to it as cam-degrees but I did. But since you shouldn't trust everything you read online I asked the question here.

Thanks!
Mike

[CJD]

I know your confusion...the Brits love to reference cam timing. If it is a US engine, it will always be in reference to the crankshaft...so balancer markings.

[CJD]

OK, finally caught up on your work...

I am not sure if the ohm meter will work as you are trying to use it. This engine uses a magnetic pick-up. I would recommend setting the crank position to the 10 degrees BTDC, and then rotate the distributor to the left (CCW) until you get a spark at the number one plug. Just set the plug on a bare part of the engine block and watch for it to spark. Try it a few times, and you will get the feel for exactly when the plug is going to spark. Then lock down your distributor at that point.

Once the engine is running, you can verify the 10 degrees with your timing light.

[chris young]

Well done CJD I never thought of doing it that way, very simple.

[roosm]

Hi again,

Okey, so this weekend didn't go as planned.
I got to the boat saturday evening and managed the initial timing setting, installing the distributor.
Then I figured it was time for a compression test.
I got lower than before on all cylinders, no idea why?
The indmar original head side read 150-160 PSI (before it was like 190-210 ?).

The opposite side, with the mercruiser head read about 130-140, except for the number 6 cylinder. This one read 70-80.

I gave up for the night, it was starting to drop close to freezing temps and it was getting late, the sauna was warm and well.. I had other things to do... =)
During the saturday evening I figured that this could be related to the valve lash adjustment.

On sunday, i tested backing off a little on the lash adjustment on no 6 and the compression read higher. Maybe about 110 PSI, I then backed it almost all the way off, where I could just spin the pushrod and I got 150-160 somewhere.
I then used an air compressor and blew air through the spark plug hole while at TDC for the given cylinder and found that most of the cylinders on the even-numbers bank at least had some small leak. Either exhaust or intake valve.
I then set all of them using my reversed method of blowing with the compressor and adjusting until right before I got a small leak through either intake or exhaust.
This is however (especially for no 6 cylinder) quite much softer than the recommended indmar tension of tightening until no play can be felt in the push rod and then go 360 degrees more.

After my new lash adjustment I got better readings around 150-160 on the even numbers bank. My final test of compression on the odd numbers bank gave me 160-180 on the cylinders. One being 160 and the other 3 all being 180.
At this point the lash adjustment for cylinder 6 is probably too soft, more like a tighten until 0 lash is felt and stop, no 360 degrees or even 180 as I have read online as another suggested method.

Another thing that felt strange was that after compression testing all cylinders, cranking the engine probably 3-4 revolutions per cylinder so lets call it 25-30 revolutions total.
The play in the no 6 cylinder was really large. Might have had a problem with the lifters sticking? And oil moving around making it different?

I kind of came to the conclusion that one plausible explaination was that the valve springs of the mercruiser head were weaker and I plan to switch the springs to the ones from the indmar head.

Any other ideas?

Mike

[CJD]

Remember these hydraulic lifters have been sitting for many weeks, so they may be at different states of "pump up". That will affect the readings before you actually run the motor and let the oil galleries come to pressure. Set them as the manual recommends.

The readings , except for #6, sound ballpark to me. The earlier ones in the 190psi range were abnormally high. At this point the rings have different amounts of oil and rust from sitting...so don't sweat the compression differences until you have run the motor and burned out the oil in the cylinders. Also, valves can get bits of carbon in the seat that will free once you run it. They will seat fully after the first run.

Guess I'm trying to say...time to run it a few minutes, and then recheck compression.

[roosm]

Hi again!

I spent most of the weekend setting valve lash according to the manual and then hooking everything up again to be ready to start. Built my own timing shunt as I didn't have any and don't know where to get one.

Today I was gonna fire up and set timing.
Crank but no start. Unplugged timing shunt and plugged in the ecm and it started right up! I finally realized my injectors are not firing when the ecu is not hooked up!
I poured a small amount of gas down the throat of the engine and it ran fine for like one second with shunt in place.

How do you get the injectors working with the ecu not hooked up to the distributor?

Thanks!
Mike