Bad news from mechanic

nyactress123

I am hoping to get some advise on this.  We had our boat overheat due to a broken serpentine belt.  We have a Volvo 5.0L OSI - EF.  We replaced the belt ourselves.  The engine wouldn't start.  Had a mechanic look at is and found that our spark plugs were sightly rusted and a small amount of water was in the cylinders. 

We checked the compression ourselves and found two cylinders low (2 @ 90 vs 150+ for the others)  Added Marvel mystery oil, went back the next day cranked the engine to blow out the oil.  Got a spritz of liquid (most likely oil)  when we did this.  We had the mechanic go back and check the compression again a week later.  They also found low compression on two cylinders, but was told it could be within tolerance.  They thought the water could have been introduced through the exhaust originally.  But before they began work, they did a video inspection and came back and said two of the cylinders had a very bad rust condition. They felt that even if the work was done on the exhaust that they can't guarantee that the boat would be ok and recommended to replace the block or engine.  

Any advice would be appreciated.

[Deleted User]

It sounds like the rust is more severe than just surface rust that could be honed out. If this was my decision I would buy a 5.7L replacement long block. Repairing your existing motor will not be inexpensive and I think the albeit higher investment in the replacement long term would be better from a resale, "peace of mind" as well as performance aspect.

Andy

F1100

run it until the engine packs it in. It could last a very long time before it does.

F1100

when it does, get a new long block and transplant the accessories ect

nyactress123

Thank you for the replies.  @andyd Do you know how long a rust condition like this would take to surface?  The boat's been hung up about 4 weeks with Marvel Mystery Oil in for the last two.  Do you think this may be something that was an existing problem before that?

boatman37

I had a friend that built a junkyard 350 Chevy for his '78 Malibu. I didn't see it firsthand but a friend of mine did and said it was so bad if you ran your knuckles up the cylinder wall you would have scrape marks...lol. He put the motor together along with a big nitrous kit and ran the crap out of that motor. It was still running when he sold it a few years later. Probably wasn't optimal but it held together.

F1100

the blocks are so cheap its really not worth pulling them out until they grenade...you will staill have all the ancillery items to put back onto another engine as long as a piston does not pack it in, and damage some valves and head

[Deleted User]

Salt water is not kind to bare metal absent oil, fresh not so bad. Not sure about how long the water would need to be in contact to do surface damage. The only motor I ever rebuilt myself was in a car that had sat for a long time outdoors in England. Rain water had entered the engine through the spark plug holes. The cylinder bores has surface rust and I was able to remove that with cylinder hone attached to a drill motor.
There was no "pitting" of the metal and the smooth surface was restored. It was an old, somewhat classic car and I was just thrilled to get it running, I wasn't looking for a reliable daily driver, and a boat needs to be reliable. I'm not a pro mechanic by any means, but I would venture to say the seal of the piston rings requires very smooth bores and any pitting of the bore would reduce compression or worse. I think an engine shop could rebore the cylinders to fix that. I've heard the 5.0L GM block is really not ideal for cylinder capacity increases, which isn't the case with the 5.7L. I'm sure others on here with more experience could chime in with their opinions.

Andy

F1100

If the engine can be turned via the crank..it will run ...see if the rings clear the rust off.. if not you are no worse off. Run it until it fails.

F1100

by the time you pay a engine shop to hone and possibly rebore the block, redeck it, and reassemble, you might as well just get a fresh long block and throw the old block in the scrap bin. If these were expensive blocks it would be a whole other story, but they are not.

pistole

whatever the condition of the two cylinder bores , how does the engine run now (or does not run at all ?). 

Poor compression , within reason , in two cylinders will not prevent that engine from starting and running.

nyactress123

Thank you.  @F1100 do you know how much a new long block would be?  @Pistole, the engine cranks, but we haven't tried to start it since the original problem.  Going to put new spark plugs in, do an oil change (we were told we had to do that) and try to start it.  We were just worried we may do more damage if we got it running, but it seems like from the responses here, that is not the case.

Willhound

Whatever damage is done is done. I somewhat agree that you could run it the way it is if it starts. Unless of course an engine failure in the area you boat in would leave you in danger on big water. If it does lock up it could be as simple as changing out the block as long as a broken ring doesn't knock a valve out or something. Then it's a block and heads.

F1100

This is the conundrum that we get into. The labour to pull and analyze whats wrong with the engine usually gets so high that its not worth trying to save the block. Its the same reason why people dont really fix things anymore, cause the labour rates to do it in some cases out weigh the material costs of a new or partially new item.

If it was an expensive engine I would say 100% start to analyze whats wrong. These v8s however are pretty cheap. And pulling the motor out, pulling it down and finding what may or may not even be a problem with stack up labour costs quick. I would run it..see what happens... If it starts to blow a ton of blue smoke...well you know the rings are shot. If the oil turns to milk..well you know your head gasket is blown. If the engine stays together and is a bit down on power.. run it until it pukes. (be safe of course on the water) It takes alot for a engine not to run if its just piston wall issue.

I remember one year in racing I needed the points in a race, and on the first lap I lost cyl 1, and the piston balled up I just stayed on it, and then piston 3 went cause of the debris from piston 1, and so on.... did my 4 lap time trial..alow...but completed it. At the end only 1 cyl(4 banger) was even working..every other cyl was balled up and the rods scraping around ..like  a bag of hammers.. of course the engine was toast but it completed the task at hand.

On the other hand.. our racing snowmobile short blocks cost 4k just for a 2cyl short block. So we would not just run them until they puke, cause the parts cost too much. Or in the case of my 911 6clyl engine... your gonna spend crazy money on a block if there is an issue.. so any sort of rod knock ect.. you would immediately shut the engine down and have it towed and fixed.

So it really depends on the motor ect..on the choices you make.

Willhound

Keep in mind guys, this is a Volvo. Blocks as cheap as a Chev/Merc ?

Handymans342

Volvo is a GM block right?

Willhound

Handymans342 said:

Volvo is a GM block right?

I dunno. That's why I was asking.

Handymans342

I believe it is the same

[Deleted User]

Yup, it's a General Motors 305 cu. in. cast iron block V8. I had a 1977 C/K Chevy truck with the 305 in it.

nyactress123

Thanks again for all the advise.  We changed the plugs and oil and got it started.  There was definitely water in the oil. Couple new minor sounds, but it's holding temperature.  Gonna do another oil change and see what happens.

F1100

make sure you put it thru its paces to make sure its not a head gasket. If it is you will know once you load the engine, and then check the oil after for contamination