165 Mercruiser, Spark, Fuel, Timed but will not start

albtross · Aug 31, 2011

Hey guys,

I've been a lurker here for a few months now. I'm a very experienced mechanic on motorcycles, small engines, cars, and have been an aircraft mechanic for 23 years but this engine has me stumped!

Here is the quick background info;

-165 Mercruiser with a cracked bloc under the manifold
-Manifold was also cracked
-Bought 250 GM truck motor with 77 000kms but not run in 3 yrs
-did a swap of all marine stuff
-pulled the head, checked cylinders, valves reassembled new gaskets.
-installed the motor with-out a snag at all
-New battery, turns over great.
-Has good spark in all cylinders
-set up timeing staticly
-rechecked the valve lash
-compression may be a little low because it hasn't run in a while but I oiled the cylinders well to help

Damn thing will not fire up even when I use Ether. It has backfired once or twice but never even tried to start.

It just does not make sense!

Does anyone have any suggestions that I might not have tried!

Patiently waiting for the genius who tells me that one simple trick and make me look like a fool!

oldsub86 · Aug 31, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

It is a simple engine.
If it has spark and fuel, it may be an issue of timing.
Do you have the distributor in correctly?

Randy

Bondo · Aug 31, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

oldsub86 said:
It is a simple engine.
If it has spark and fuel, it may be an issue of timing.
Do you have the distributor in correctly?

Randy

Ayuh,... That's My guess,... Yer off on the distributer by a tooth or More...

Volphin · Aug 31, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

Yepper. Dist is off.

V

stonyloam · Aug 31, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

albtross said:
Damn thing will not fire up even when I use Ether. It has backfired once or twice but never even tried to start.

If it is backfiring I would look to the timing. Sounds like it is way retarded. Mark the #1 cyl on the side of the distributor, bring it to TDC compression, remove cap, is rotor pointed exactly at the mark?

Fishermark · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

I agree with all of the above - in fact, mu money would be on the distributor being 180 degrees out. Turn it 180 and see what happens.

Don S · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

-compression may be a little low because it hasn't run in a while but I oiled the cylinders well to help

180 out on the distributor is probably the cause, but????????

What is your compression numbers? Are you positive you adjusted the valves per spec? Did you have the engine on #1 TDC of the compression stroke? (not the exhaust stroke). If you were off on that, you would have low compression on some cylinders, and it would never start.

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

I thought of that but the distributir on this engine drops into a keyway similar to a common screw. It is offset so it can only go in one way. When I first installed it it would not sit all teh way down inside. When I removed it I could see that it was 180 degrees off. I will pull out the distributor and double check it again to be sure I didn't miss something.

Iam not too worried about compression numbers right now because even with 0 PSI it should fire with ether spray in. I expect the compression to be a little low until it runs a bit and loosens up. It has not been run in 3 yrs.

Does this makes sense to most of you?

Fordiesel69 · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

Double check the distributor timing as mentioned. But old engines can be super stuborn to start if the lifters have collapsed. They can take time to pump up.

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

I did have the #1 at TDC on compression when I timed. I actually went through the whole valve timing a second time to be sure. I will put the compression gauge on it after I double check the distributor tonight.

I know it has to be something simple because this engine is as simple as they get!

Thanks for the ideas, keepthem coming and I will post what I find. gotta hate posts that don't follow through and give the answers to the problems, regardless of how embarrassing they can be.

Don S · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

Read this on finding #1 TDC on the compression stroke. The distributor can fit in on any tooth, just a matter of lining up the oil pump where you want it.

http://forums.iboats.com/showthread.php?t=427081

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

I was worried about this too. This is the first lifter engine I have worked on. All others have been overhead valves. It has turn over plenty. It has good oil pressure because oils is being pumped up to the head and rocker arms. I searched this forum and others for advice on setting the rocker arms up. I set them at 1/4 turn after resistance is felt on the push rods and will adjust after it is running if needed.

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

That is a real simple way to check, isn't it!

I'll do it this way tonight.

Thanks very much.

Gotta love using work time to solve problems at home! Low motivation for work today I guess.

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

This is what the end of my distributor looks like. It can only go in one of 2 ways or am I missing something?

Volphin · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

You know, sometimes I still screw up and put the plugs in the wrong locations on the distributor cap. It is very humbling. LOL Double check that too.

V

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

Bubba1235 said:
YES. The bottom tab drives the oil pump, it's position doesn't mean anything to the ignition timing. (You can stick a long screw driver down the hole and turn the oil pump.

I see what you mean now!

This is probably the problem. Thanks.

I am so excited I should leave work early to go fix this.

albtross · Sep 1, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

This was one of the first thngs I checked. I did get it right.

albtross · Sep 2, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

So,

The distributor was off a tooth. I thought yehaah, this has got to be it! Damn thing will still not fire up, so for the fun of it I checked compression in all cylinders. 1 and 6 have 120psi which is pretty good for an engine that has not run in 3 yrs. 2,3,4,5 read 0 psi. I would think this is valves, not piston leak. I put oil in the cylinder and tried again with no change.

Looks like a head rebuild. Do you guys think I am on the mark here?

You would think it would still fire with ether spray in but it didn't.

Don S · Sep 2, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

You should have been able to hear that problem just in how it cranked over.

BEFORE you start yanking it apart without a clue as to why you have 0 compression on 5 cylinders try this. Remove the valve covers ands crank the engines. Do all valves move? If they do, back off all the rocker arms so there is about 3 threads showing above the adjustment nut and try your compression test again.
It really sounds to me like you have the valves adjusted all wrong.
Do you have a manual for this engine?

FreeBeeTony · Sep 2, 2011

Re: 165 Mercruiser, Spark, Fuel, Timed but will not start

Are you sure the valves are not adjusted too tight?

165 Mercruiser, Spark, Fuel, Timed but will not start

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