No compression

[Marty Levenson]

Hey Guys,

Met a young couple on the dock today who just bought their first boat. There is a great looking A4 that won't start. They were told it hadn't run in a few years. turns over fine. Their local mechanic told them there is no compression and that he needs to take the engine out.

Shouldn't they try loosening the valves first? Take off the valve cover, spray some penetration oil, persuade the valves to loosen up? I haven't had to go that direction as of yet, but picked up that idea from endless lurking here.

Thanks!

[Dave Neptune]

Marty, absolutely suggest they give resurrection a try. My engine had been frozen for a few years when I bout her and once I got her to spin she ran well for 35 years for me and is still getting the new owner around. Well worth the effort!!!

Get them on the forum if you can.

Dave Neptune

[JOHN COOKSON]

Met a young couple on the dock today who just bought their first boat. There is a great looking A4 that won't start. They were told it hadn't run in a few years. turns over fine. Their local mechanic told them there is no compression and that he needs to take the engine out.
Thanks!

How is there "no compression"?
Low compression across the board that improves when oil is added to the cylinders?
No compression in two adjacent cylinders?
No compression in two non adjacent cylinders?
The first thing I'd do is repeat the compression test myself.

TRUE GRIT

[Marty Levenson]

compression

For my own knowledge base:

"Low compression across the board that improves when oil is added to the cylinders" = mediocre rings?

"No compression in two adjacent cylinders" = likely head gasket or head issue?

"No compression at all" = stuck valves????

Thanks!
Marty

[JOHN COOKSON]

For my own knowledge base:
"Low compression across the board that improves when oil is added to the cylinders" = mediocre rings?
"No compression in two adjacent cylinders" = likely head gasket or head issue?
"No compression at all" = stuck valves????
Thanks!
Marty

Yes. Just want to know what issue we are addressing so we know the fix.
If there is no compression in just one cylinder the cause is most likely a stuck valve.
Did the mechanic explain why the engine needed to be pulled and the compression problem could not be fixed in situ?


TRUE GRIT

[Hymodyne]

I have had a lifter stick and cause no compression too.

James

[JOHN COOKSON]

Marty
Echoing what Dave N. said; have these folks join the forum so we can deal with this on a one on one basis.
Few mechanics are honest and competent. Most aren't worth a pitcher of warm spit when it comes to A4s. Afourians excepted, naturally.

TRUE GRIT

[BunnyPlanet169]

Hey Guys,

Met a young couple on the dock today who just bought their first boat. There is a great looking A4 that won't start. They were told it hadn't run in a few years. turns over fine. Their local mechanic told them there is no compression and that he needs to take the engine out.

Shouldn't they try loosening the valves first? Take off the valve cover, spray some penetration oil, persuade the valves to loosen up? I haven't had to go that direction as of yet, but picked up that idea from endless lurking here.

Thanks!

You are absolutely right on. Good looking engine and turns over says fix it in place if you can. Pulling the engine is $$$ and a year out of the water.

As others have said, get them online, and maybe loan them your MMI manual for a few days....

[Marty Levenson]

compression

Thanks for the replies.

Yes, they have the manual and tools, and I have strongly urged them to join the forum. I am hopefully meeting them later today, so wanted to be sure my advice was sound. Loaning them penetrating oil and gaskets.

The mechanic was also the p.o.'s mechanic, and has been responsible for the A4 for a while. His work looks very good. New owners told me he plans to pull the engine and fix and reinstall within two weeks. I am also encouraging them to see this as a learning opportunity as they plan to cruise extensively and have little experience. They seem eager to learn and ask lots of questions. Showed them what to do to remove the carb, and then the valve cover, and they plan to do that. I have to say the access is terrible on that part of the engine (C & C 33).

Engine was running last fall, and it is fresh water cooled, so seems unlikely the gasket failed over the winter....? Time permitting I will run my own compression test, as they seem a little vague on the details.

Well, hopefully they will pick up the thread soon.

[romantic comedy]

Some red flags.

Take out and fix within two weeks?
Sounds like he knows exactly what is wrong and just wants to make it look good and get more money. Doubtful!

He needs to remove head and see what is going on, so he can give an estimate of what it may cost and what is needed to get it going. Rebuild? Valve job? just stuck valves? Big difference in cost and time.

Just knowing an engine has no compression a mechanic cant give an estimate of the repair. More diagnoses needed to be done.

[Marty Levenson]

have compression - no spark

Atomic Brainiacs,

Looks like the mechanic was pretty far off. I was on my friends' boat today and took them through some initial troubleshooting. Found there was no spark cranking and holding the plug to the block. Opened the distributor (was converted to EI) and found the rotor looked shot - worst I've ever seen. Had a spare rotor to try, but still no spark. While the plug was out cranked and felt my thumb pushed off by compression.

My question at the moment is: Noticed the coil was quite warm at the top although cranking was maybe two x 30 seconds. Is that indicative of a coil problem?

I had to take off but left a spare coil and distributor cap for them to swap out.

I suspect tomorrow we'll be exploring the gas supply once we have spark - didn't smell any fuel after cranking. I think the mechanic changed the racor filter, so maybe it was still empty and needs more cranking to fill. I know you are supposed to pre-fill, but assuming nothing.

The other issue is that the batteries sound low: cranking but not as fast as it should.

Queston two: Can a low battery still create a good spark?

[Al Schober]

Marty,
Sounds like these folks should be hiring you as their mechanic...
I don't have EI, but a hot coil after 60 sec of cranking doesn't sound good. How long was the key in the ON position (assuming current to the coil the whole time)?
Sounds like you're back to the basics - compression, spark, fuel. And it sounds like you may have issues with all three. Personally, I'd address the compression first - likely to be the long pole in the tent!

[Marty Levenson]

tracking it down

Having fun helping out ...plus the boat karma thing.

I left my compression gauge with them, and they figured out how to use it. Quick learners. They just called to report that all cylinders have 85-100psi! So, compression is good.

Thanks for the thought about the ignition left on - that might explain the heat.

New owner also reports plugs were wet w/gas - so that's looking good.

They also migrated their ignition wires to the spare dist cap I left there, and report now yellow spark at three cylinders, and a whiter spark at one. Wish I had thought to bring my meter!

So can bad coil and/or low battery = poor spark?

Thanks!

[Marty Levenson]

spark

....poor negative ground?

....failing ignition wires?

....or....?

[JOHN COOKSON]

Do a check of the distributor towers to see if there is any corrosion in them that is making the weak spark. The little rubber boots on the towers do not make a100% moisture proof seal.

TRUE GRIT