Blow-by on 1988 Mercruiser makes engine stall

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

The heads are off. I do not see anything obvious wrong. The heads look fine and there did not appear to be anything wrong with the gaskets. Some of the silver stuff on the bottom stuck when I removed them. What should I be looking for? The cylinders and the top of all of the pistons look fine. No ridges.

Where do I go from here?

John

 

[Yepblaze]

Re: Blow-by on 1988 Mercruiser makes engine stall

Just run it like it is or sell it.

By watching your level of understanding, I am not too sure you will succeed with self repair.

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

Just run it like it is or sell it.

By watching your level of understanding, I am not too sure you will succeed with self repair.

I'm not sure what you mean by this. It is a little late to run it as is and I would never sell a problem like this to anyone.

I am actually leaning toward a long block from Rapido Marine.

 

[captmello]

Re: Blow-by on 1988 Mercruiser makes engine stall

If it were mine, I'd rotate the engine around to get a look at all the cylinder walls. If you don't find any scoring and all the pistons go up and down, take the heads to a machine shop and get them checked out.

Just my opinion.

 

[system-f]

Re: Blow-by on 1988 Mercruiser makes engine stall

Although I only have one headgasket I had similar problems and it cost me a total of $200 and about 10 hours worth of work to get my engine going.

If it is really wore out, why does it run so good above an idle? It powered my 24 foot Cruisers to 38 MPH at 4500 RPM without a sputter or any hesitation.

I do not know. My straight 6 had only TWO healthy cylinders and 2 that were marginal and it would start up within half a second even when cold and even idle!

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

Although I only have one headgasket I had similar problems and it cost me a total of $200 and about 10 hours worth of work to get my engine going.




I do not know. My straight 6 had only TWO healthy cylinders and 2 that were marginal and it would start up within half a second even when cold and even idle!

What was the actual problem? Was it obvious when you took it apart?

 

[solar7647]

Re: Blow-by on 1988 Mercruiser makes engine stall

Thanks again for all of the responses. I really did not think that I was going to dig in this deep, but I guess I will start tearing it down tomorrow morning.

I still have to ask this. How can this thing run this good if it is this broke? 4500 RPM and 38 MPH. What should expect when it is perfect? I still do not not get how it can run this good. I never even expected this boat to run 38 MPH.

John

Well as long as you have spark and fuel it will still fire and force rotation of the crank. When you get it fixed and have all your torque and Hp back you will see a huge difference in hole shot, control and speed. I am sure you will be pleased with the results of an overhaul...just make sure you measure the cylinders bore before getting and parts... with a 0 compression reading you could have some serious cylinder damage.

Let us know what you fine. Good Luck

 

[system-f]

Re: Blow-by on 1988 Mercruiser makes engine stall

What was the actual problem? Was it obvious when you took it apart?

Go to the rebuild section and look at the poor man's skiboat restore or use the link in my signature. I have pictures and a description of everything that happened. IT was a blown headgasket, warped head and leaking exhaust valve seats. Basically someone overheated the engine big time.

 

[solar7647]

Re: Blow-by on 1988 Mercruiser makes engine stall

The heads are off. I do not see anything obvious wrong. The heads look fine and there did not appear to be anything wrong with the gaskets. Some of the silver stuff on the bottom stuck when I removed them. What should I be looking for? The cylinders and the top of all of the pistons look fine. No ridges.

Where do I go from here?

John

What you need to do is using your finger tips press firmly on the center of the piston head and see if you can move it side to side in the cylinder. This is best done with the piston at full stroke. The piston should be very tight in the cylinder, a good one will only just wiggle a very little if at all. If it has side ways movement (left, right, forward or backward) you have a bad rings or a warn cylinder. ....To find witch problem you have the next step is to use calipers to measure the cylinder bore and compare to the engine spec.....if its out of tolerance you will need to machine or get a remaned block. If it is you just need new piston rings....

 

[Yepblaze]

Re: Blow-by on 1988 Mercruiser makes engine stall

I'm not sure what you mean by this. It is a little late to run it as is and I would never sell a problem like this to anyone.

I am actually leaning toward a long block from Rapido Marine.

because you said

The engine runs great at anything above an idle.


John

that's why

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

The heads are at the machine shop. I have used him to bore many Jet Ski motors that I have rebuilt. He is also willing to do a complete rebuild if just fixing the heads does not fix the entire problem. Initial Inspection, no cracks and a bad valve in the cylinder that had 0 compression. I will let you know when I get the heads back.

John

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

I got the heads back and installed them. The weather here has been horrible. I finally started it today to adjust the valves. It ran for about 2 minutes and quit. There is now no spark. There is 12 volts on the + side of the coil and there seems to be nothing on the - side when checked with a volt meter. Am I missing something obvious? Is there a simple way to diagnose this?

 

[captmello]

Re: Blow-by on 1988 Mercruiser makes engine stall

Glad you got it back together. I'd like to know what kind of compression you're getting with the new heads. Did you get the valves adjusted??

No spark? Need info on the ignition system. Points? You may want to start a different thread.

Good Luck!

 

[Don S]

Re: Blow-by on 1988 Mercruiser makes engine stall

You DO NOT have to run the engine to adjust the valves. You might not even get it started or keep it running because of the valves. But they will not cause you to loose spark. I have to assume you didn't go up to the Adults Only sticky and download the OEM service manual.
If you did, then you would know how to adjust the valves without the engine running, and you would also know how to troubleshoot your no spark problem. Even a chart on page 4B-18 of manual #9.

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

Electronic ignition. The control module is mounted on the riser. It is strange that It ran fine and then stalled. Could I have damaged something when I was checking the compression? I had the coil disconnected.

 

[Don S]

Re: Blow-by on 1988 Mercruiser makes engine stall

Looks like we were typing at the same time. Go up to reply #45

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

I did download the manual. I will take a look at this section.

Thanks, John

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

The problem was the ignition sensor in the distributor.

 

[captmello]

Re: Blow-by on 1988 Mercruiser makes engine stall

The problem was the ignition sensor in the distributor.

Good, so whats your next move??? Did you get it running again?

Let us know.

 

[JohnCiccarelli]

Re: Blow-by on 1988 Mercruiser makes engine stall

I did get it running. I am waiting for the mechanic that did the heads to adjust the valves. I have never done it before and I want it done right. He plans to do it this weekend.