Low Compression on Survey

dcharna

dcharna

New Member
Aug 4, 2011
208
Lake Erie - Catawba Bay
Boat Info
2003 Sea Ray 340 Sundancer
Engines
Mercruiser 8.1's 370 hp
All,

I am in contract on a 2007 Sea Ray 290 Amberjack. The survey went amazingly well until we got to the engines. The boat is in perfect condition, dry as a bone etc.. I had Marine Max do compression which came back bad. The owner had his own service company repeat the tests as follows:

PERFORM COMPRESSION TEST
PORT #1 170 #2 175 #3 130 #4 100 #5 170 #6 170 #7 165 #8 175
STARBOARD #1 100 #2 165 #3 160 #4 180 #5 180 #6 175 #7 165 #8 115.
SQUIRT OIL DOWN THE LOW CYLINDERS AND CHECK COMPRESSION AGAIN.
NO CHANGE
CYLINDER HEADS NEED TO BE REMOVED AND VALVE JOB PERFORMED

The boat is powered with 5.0L Mercs with Bravo III drives. The boat only has 440 hours on them. Always stored in heated indoor storage.

I have so many questions including:

1. Why would these engines have such premature wear
2. Why would both engines go at the same time
3. If they perform the valve job, should I be concerned about these engines or happy that this was done.
4. Would you walk away.
5. Any other advice that I don't know to ask

Thanks for your help on this!!!!

Dan
 
How did the sea trial go?
Were the engines making any noise ?
How cheap can you buy it for ?

A bore scope would tell you more. Heads only not that big a deal. If the bores don't look real nice, or if there's any motor sound when it's running, plan on a repower.

It's all about the price you can get it for
 
There are several causes for low compression numbers. Some are expensive to repair; some not so much. Just doing a valve job might not correct the problem. For example, what if the risers and manifolds have leaked sea water into the cylinders and the cylinder walls are scored and pitted and the valve seats are rusted......the engine would need to be rebuilt or replaced. For that reason, I think your best option is to refuse the boat and cancel your contract, but tell the seller you will accept the boat under the terms of the contract (assuming the boat is otherwise acceptable under the contract terms) after he has had the engines repaired and the compression retested and found to be normal. The best outcome of your refusal is that you will leave your deposit in place then amend the contract stating that the seller will repair the engines, furnish you receipts for the work and then you will have the compression retested at which time you will complete the deal if the resurvey results suit you.

In negotiating deals like this, the seller has no cards. With survey results like this, he has a boat that will not sell to anyone and he and his broker know it. You are his best chance of getting it sold so he really has no options other than to make the deal with you work.
 
The Merc # of a 100psi. is a complete joke.

Vortec headed v8 should be in the 180 lb. range

Pre vortec v8 150psi is a healthy engine

!00 # psi motor is toast, bore it or toss it
 
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The engines could be carboned up in the valves and rings. In my 28 footer I had a problem with one engine. I lost power. It was towards the north end of Vancouver Island. We pulled into a remote government dock and there was a boat there that was owned by a Triple A Dragster driver. He and his mechanic looked at my engine and said it could be a carbon problem. He then took 20 OZ of water told me to keep the RPM at 1500 and poured the water into the carb. Before we did that I had 1 cylinder at 90 PSI and 1 at 125 PSI. The rest were 165 to 170 PSI. He told me putting the water in the engine would do one of two things. Blow it up or knock the carbon out of it. Well after 15 minutes all cylinders were 150 to 170 PSI. Engine had around 1000 hours on it. Just a thought for the owner to consider. It is his boat and his decision. New engines are 20K each installed I have been told for my boat. You might want to see if the price could be reduced by the cost of new installed engines and try to fix the problem without replacing the engines. If you can not you have the money in the reduced price.
There are lots of boats out there. A problem with engines at low hours could indicate neglect and that could be in other areas of the boat also.
 
Suggestion on getting answers. The computers should be recording not only actual hours but the % of rmp ranges. The engines with high rpm averages have been abused by the owner. Engines should not be run over 80% of full rpm for long periods of time.

Mark
 
Walk away. Trouble looms. Valve jobs don't fix cylinder compression. Get it scoped. You'll know then. Also oil analysis will reveal where wear is from.
 
Read my "autopsy" thread - just went through this - especially adjacent cylinders........what about a leakdown test - that will tell if its the heads or not......if it needs long blocks its probably going to be around 15k for both. To answer your questions #1 - were they fogged at layup - manifolds ever replaced? service history? overheated? #2 - same age/use #3 no concern if that is the problem and it is done right......although some people say a "new" top end will wear out an "old" bottom end quicker #4 No - Might be a great opportunity to get a great price an "new" mechanicals at the same time #5 as above oil samples and leakdown tests performed by someone working for YOU not the seller are key
 
Just do what Frank said, you can't go wrong there. There are too many variables for low compression. My son is finding that out with his MazdaSpeed 6. As he tears into the motor I keep getting smarter....
 
Don't care what the boat looks like I'd be walking away we buy boats to go boating not fix em.move on.
 
fwebster said:
There are several causes for low compression numbers. Some are expensive to repair; some not so much. Just doing a valve job might not correct the problem. For example, what if the risers and manifolds have leaked sea water into the cylinders and the cylinder walls are scored and pitted and the valve seats are rusted......the engine would need to be rebuilt or replaced. For that reason, I think your best option is to refuse the boat and cancel your contract, but tell the seller you will accept the boat under the terms of the contract (assuming the boat is otherwise acceptable under the contract terms) after he has had the engines repaired and the compression retested and found to be normal. The best outcome of your refusal is that you will leave your deposit in place then amend the contract stating that the seller will repair the engines, furnish you receipts for the work and then you will have the compression retested at which time you will complete the deal if the resurvey results suit you.

In negotiating deals like this, the seller has no cards. With survey results like this, he has a boat that will not sell to anyone and he and his broker know it. You are his best chance of getting it sold so he really has no options other than to make the deal with you work.
Click to expand...

Excellent post and spot on.

I just went through this situation with a freinds boat.
Some low compression numbers on both engines.
I was contracted to go retest what was reported.....wasn't good.
I suggested he pull the heads and see what it looks like, warning him that it maybe just heads or a new long block (or rebuild). A couple grand or several grand but, won't know until we look....?

The buyer loved the boat and bought it for a price that left room for a complete rebuild on both engines.
Seller wasn't thrilled but, knew it wasn't going to sell with low compression.

Buyer dropped me a line that after all heads were referbuished all was fine and running well.
 
Thanks everyone for the great information. I walked away yesterday. Actually met the seller as well. Meticulous person. Kept a log of everything he has done to the boat maintenance wise. Professionally serviced. Bought fuel from the same place I buy fuel since the boat was new. He is flabbergasted. He is fixing the boat and will put it back in the water this spring and try to get some enjoyment out of the 5K + he is going to have to spend.

Happy New Year,

Dan
 
Not at all uncommon.
Boats commonly get a little rust on the valves from the moist air and little use.
Or, some water seeping in from failing exhaust gaskets.
A top end or valve job isn't the end if the world.

This is one reason why we fog the engines in the winter or anytime of prolonged storage.
It helps to run your boat up to operating temp often to circulate the oil and dry out any condensation.
 
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