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0 compression in one cylinder, told to replace engine

W

waterlover

New member
Hello,

Long time lurker first time poster.

Let me preface this by admitting I'm not a mechanic by any stretch of the imagination.

Here's my problem. I'm in Dubai (from the States), and the lack of quality marine services here is unbelievable! The city is great, but this one area is waiting for the right company to come in and takeover.

I brought over a Carver 350 Mariner (1999) with 380 hours on twin Crusader 454 xli 7.4L engines.

Long story short, the starboard engine is running like a champ, but the port engine constantly overheats. After the first time it overheated, I kept it docked and tried to get it fixed (unsussesfully). After replacing the valves, risers manifolds, u cooler etc... it's still running hot and has as constant clicking sound.

After begging for a compression test from the first three mechanics who had no idea what I was talking about, the last mechanic came and did one unsolicited. 150 all around but 0 in the 5th cylinder.

The worker wanted to open the topside to see if (and here's where I show my ignorance) it was the rocker or something that could be fixed while the engine remained on the boat. The owner of the shop said the engine would have to be removed, but refused to do it because he feared running into a lack of parts situation. Let me explain. Apparently there are no trailers in the country capable of handling shaft drive boats (multiple mechanics story, not mine), so the solution would be to have it lifted at the local yard and the engine worked on there. The daily expenses are very expensive there and if we needed a part, the wait time could really add up.

So I was told to buy a new engine from the States and they would swap it out with the bad one. No more no less.

The other well known shop here came to look at the boat but had never heard of Crusaders and wouldn't touch them. They only work on Mercruisers.

So here's my dilemma, buy 2 Crusader engines from the States and have them swapped out, or put in 2 Mercs instead.

I chose Crusader because of the closed cooling and avoided the Mercs because the water's extremely salty here. The good thing about Mercruiser is they're well supported here.

Also, I'm thinking the Crusaders have 4 bolts for the engine mounts and the Mercs 2. Not sure how hard this would be to fit and the time it would take dockside.

So there's my extremely abbreviated story.



Thoughts from the experts?
 
A Crusader 454 and a Mercruiser 454 would essentially be the same engine .-----Not sure why a shop would say " we will not work on it "
 
Pulling valve covers for the purpose of looking at the rocker arms or valve springs would be protocol.

Next would be a "cylinder leak-down" test, as a "compression" test only reveals that a cylinder IS or is NOT making compression.
The "leak-down" test will indicate where/how the cylinder pressure is bleeding off, or what it causing it to NOT build!


.
 
We have a similar situation in Mexico, where marine mechanics are familiar with diesels and outboards, but not US sourced gas engines. You need to find an automotive mechanic for advice and assistance. You engine is basically the same as what was then put into Chevy Suburbans and pickups. There must be someone fixing those over there.
 
racerone said:
A Crusader 454 and a Mercruiser 454 would essentially be the same engine .-----Not sure why a shop would say " we will not work on it "
Click to expand...

That's the same thing I said. And to be fair, it was the only shop that refused to touch it. It just so happens they have the best reputation, location and facilities to handle the job.
 
RicardoMarine said:
Pulling valve covers for the purpose of looking at the rocker arms or valve springs would be protocol.

Next would be a "cylinder leak-down" test, as a "compression" test only reveals that a cylinder IS or is NOT making compression.
The "leak-down" test will indicate where/how the cylinder pressure is bleeding off, or what it causing it to NOT build!
.
Click to expand...

That seems to be the guideline the mechanic was following before his boss said they wouldn't proceed further and the only course of action would be to remove the engine.

Besides the loss of compression, there is that constant tapping sound and the engine will overheat if left running more than 10 minutes.

My question is, is it at all possible this is not a problem that needs solved by removing the engine? Wether it be the rocker arms or something else, would any diagnoses from here on require as a fix the engine be removed?


Thanks for the help.
 
CaboJohn said:
We have a similar situation in Mexico, where marine mechanics are familiar with diesels and outboards, but not US sourced gas engines. You need to find an automotive mechanic for advice and assistance. You engine is basically the same as what was then put into Chevy Suburbans and pickups. There must be someone fixing those over there.
Click to expand...

Looks like we're in similar boats. There are a lot of mechanics who will work on the engines here, but most would be able to handle the small scale items but enter the guessing game when it comes to diagnosing anything. Out of about 5 companies, only one knew what a timing light was or a compression test.
 
Thanks,

And while I search for someone who can do this, is there any outcome that wouldn't require access to the bottom of the engine?

I ask this because if the engine has to come out in any case, I'll be getting a new one.
 
There is a good chance that the engine does not need to come out. A leak down test tells you where the missing compression is going which is valuable information. If you find it is into the crankcase (indicating holed piston, fractured rings, or cracked block) then the engine will need to come out. But if the lack of compression is a valve train problem (a more likely cause) then sometimes it can be fixed from above but usually will require removing the head. The head can usually come off without pulling the engine from the boat.

You will still need to run down the overheat issue which quite possibly is the root cause of whatever failure has brought about the loss of compression. In your first post you said " After replacing the valves, risers manifolds, u cooler etc... it's still running hot and has as constant clicking sound." Did they really already pull the heads and replace the valves or were you referring to something else being done? Did the noise start after they worked on the engine?
 
The engine had overheated when I first got it but didn't happen again. As a precaution, I replaced the manifolds, elbows, oil coolers and had the cooling system acid washed. Everything was fine but the engines were only going to about 2800 rpm and about 17 mph. The mechanic said he saw water in a couple of the cylinders and I should get a valve job and head job.

After he had the valves done, he said one of the cylinders was operating at max capacity because of a small fitting he forgot to bring. He said the problem was minor and should correct itself anyway. During the sea trial, the good engine reached max rpm and the bad engine got to about 3800 rpm and I was getting about 22 mph.

After going out twice, the engine overheated. We shut it down and came back on the good engine. We turned on the bad engine to park and it was fine. Then it shot up to 200+ degrees. We shut it down and parked. The coolant had boiled out as it had when it overheated when we wereout.

Called another mechanic and determined the engine overheated after about 11 minutes and the heat exchanger was to blame. I paid to have it boiled out but it didn't fix the problem. This is when they heard a ticking and warned I'd have to remove it.

They blamed a bad gasket (which the first mechanic replaced).
I called the first mechanic and he said I had 2 bent valves and replaced them. After all was complete, he also heard the ticking and warned I had a bigger problem.
 
Doesn't sound so good. The sequence of events is a little murky and it is important. If the water (presumably salt) was seen in the engine before the work then likely this was leaking elbows, something that needs to be replaced regularly regardless of engine hours. Clogs also are a product of corrosion in the elbows and this can cause poor raw water flow and overheating. So maybe that explains the initial issues. After the head/valve job was done you only got 3800 rpm. So likely you were running on 7 cylinders, which means the engine work and the sea trial were failures. I can't understand the “small fitting” comment but it does not inspire confidence in the work.


You found out later that in the head work they found two valves were bent, which means the engine may have seen severe stress. The damage could have been due to corrosion on the stems from the salt water from the leaking elbow causing the valves to stick down and get hit by the piston, or from severe overheating causing damage to the head, or whatever. Anyway, inspecting the head and replacing the damaged parts should have fixed it but did not.


Now you are seeing overheating again, which should be gone (assuming they have confirmed you have good raw water flow (no clogged intake, collapsed hoses, bad impeller, or slipping belts....because everything else is clean or new). And you find coolant missing, which you assume is the result of overheating, but actually might be the cause of the overheating. Missing coolant goes somewhere, either into the bilge (out the cap when it boils), or into the oil or the exhaust if it comes through a cracked head or block (they may have missed the crack when they had it apart). And you have a ticking, which could be another stuck or bent valve (if they missed a damaged head) or perhaps just a poorly assembled valve train. Or the noise could be from lower end damage (damaged bearing, cracked cylinder wall, etc.) which is bad news indeed.


You are attacking three issues, overheating (or perhaps missing coolant), lack of compression in #5, and the ticking noise. You have to find and fix all three.


I would inspect the oil to insure it is not milky with coolant. If so, I would stop there and order the new engine. If it is clean, do the cylinder leak down test to see if air is leaking into the crankcase or into the coolant system. If it is into crankcase, stop and order the new engine.


If the recommended cylinder leak down test says that the compression problem is valve related, that still does not mean you don't have a crack in the block or head causing the coolant loss. I would pressure check the coolant system and see if it holds pressure, and if not, where the leak might be. If you have a pressure leak, hope it is a cracked head and not a cracked block.



Next, fill it with coolant, pull the valve cover on #5, fire it up, and see what you can see. Hopefully you will find the cause of the ticking noise. Use a rubber hose as a stethoscope. If a valve is not working it could be stuck/bent and just barely contacting the piston. If they work you could try loosening the rocker arms and turning them to kill valve action and see if that makes the noise go away. You really would like to find the noise since it would be a shame to pay to fix the top end only to later find you have bottom end damage and have to scrap the engine.



But whether you find the noise or not, you will likely have to pull the head on that side. We are getting into a lot of what if's now, and I don't have the time or imagination to cover all of them. But given the failure of the past repair you will likely have to replace that head with a rebuilt one. And if at any point in the process you decide the noise is lower end, likely you should give up and replace the engine.


Good luck, and you may get some additional comments on the forum suggesting additional diagnostic actions you might consider.
 
Wow, thanks for the detailed response and instructions. I appreciate the time you took to write this.

I'll print this out and take it to the mechanics who are fixing my generator.

I'll post the results etc... as I get them.

Thanks again!
 
I am not all that familiar with inboards.------But what direction does this engine rotate ??----Regular or opposite to automotive ?
 
racerone said:
I am not all that familiar with inboards.------But what direction does this engine rotate ??---- Regular or opposite to automotive ?
Click to expand...

A Standard Marine Engine will be LH rotation.... rotating in the same direction as automotive or industrial.
An exception to this will be with the earlier twin I/Bs whereby the Starboard engine is often RH REV rotation.
This is subject to change with some V-drives and OER (oposite of engine rotation) transmissions.

Rotation is always viewed from the flywheel end..... whether Marine, Automotive or Industrial.

Standard LH rotation on the left...... RH REV rotation on the right.
 

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Regarding overheating. Have you checked the bottom to make sure the intake is clean and not covered up in growth? And the sea strainer? Perhaps you have restricted waterflow, overheated, cooked it and hearing the bent valves?
 
TeKeelA said:
Regarding overheating. Have you checked the bottom to make sure the intake is clean and not covered up in growth? And the sea strainer? Perhaps you have restricted waterflow, overheated, cooked it and hearing the bent valves?
Click to expand...

Yes, checked these things first when the engine initally overheated. Had my friend dive down and check but all was clear.

Thanks for weighing in.
 
waterlover said:
This is one of the companies I was talking about. Make appointment and pull a pull a no show. No call, nothing. And no response to emails.



Thanks for the leg work though.
Click to expand...


I just called again to double check. There response is their entire team is off shore for months and they don't know when they'll be back!
 
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waterlover said:
I just called again to double check. There response is their entire team is off shore for months and they don't know when they'll be back!
Click to expand...
They look like a big time industrial outfit. I was surprised when I saw they work on Crusader in boards. It can be just as hard to find someone in the States during the "season". Unfortunately,you don't have many options.
 
tomnf said:
Could an exhaust rocker be too tight to open and close as normal?
Just asking cuz I aint a mechanic?
Click to expand...
It could, but what would the cause be?

A rocker arm may become loose causing excessive tip-to-valve-stem clearnace.
Seldom would one become too tight unless a valve was to start sinking into the valve seat.


.
 
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