Head Gasket Blown - How much damage to expect?

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Quigs

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Hi - Ive certainly had a year of it this year with continual problems with my boat and to top it off, it looks like the head gasket has gone on my Mercruiser 5.7L EFI. (Compression non-existant on Nos. 2&3 on the starboard side)

Now, before I go and spend £000's on a new engine I was thinking about stripping off the head and having a look at the damage. I reckon if it is just the gasket, a couple of new gaskets, new manifolds,risers etc for both sides should cost me about a £1000. However if water has found its way into the cylinders what sort of damage can I expect and is it really worth repairing?
 
You can buy a non marine short block for about 2k then another 1k for the manifolds and risers, now I have one in a poor state in my workshop, the owner wont pay to have it done, I enquired with Dave Crawford marine in Lymington he said he could do me a new engine for around 4k complete with warranty etc, so its not really worth an overhaul unless you can get away with just rings and a gasket set.
 
This is what I thought, Coastal Rides have a 5.0MPI which still has 260hp for 4K+VAT. Hes offered to lose the VAT in exchange for my engine. I just wondered if I could get away with just new head gaskets and risers if damage is not too great.
 
Speaking with no direct experience with a marine engine (but two cars with replaced gaskets):-

1 - you won't know until you get the head off!

2 - Do it soon so that water can't sit in the bores for long, leaving a rust ring (This happened to my XR2, it did run again, bur never quite as well!).

3 - Iron block deisel engine is unlikely to have suffered any damage. I expect the head will be iron too, so umlikely to see any scoring or warping.

4 - Why consider replacing manifolds, risers, etc.? Should be only the gaskett to replace, unless some other underlying problem - in which case a new engine is probably more cost-effective!

See what others say.

Good luck!
 
I wouldnt buy a spring washer from them, forget it trust me.

Secondhand parts sold as new, reconditioned engines just steam cleaned and painted, I could go on.
 
Please do go on, was considering them if I ever needed parts.... /forums/images/graemlins/confused.gif

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I wouldnt buy a spring washer from them, forget it trust me.

Secondhand parts sold as new, reconditioned engines just steam cleaned and painted, I could go on.

[/ QUOTE ]
 
Well thats blown my estimates out of the water cos the nearest I can get to a new engine from other places is circa £5.5K, unless I import direct from the US of course!

Anyone done that before?
 
A lot depends on if it is seawater cooled or freshwater cooled, if the former it is probably game over. If the seawater has been pumped round with the oil then all of the bearing surfaces will be damaged, and its not worth repairing.
If the latter then a strip down and clean and rebuild should sort it, making sure that there is no problems on the manifolds and risers as you don't want these to leak seawater after doing so much work on the motor.
If the gasket is visibly blown you should be OK, if not then get the head checked although these cast iron heads and blocks give very few problems that way, and make sure the bores are OK, have seen loss of compression from broken rings scoring the cylinder.
 
Alternative suggestions..........
If no other symptoms other than no compression, you may have "tulipped" a couple of valves, or blown the gasket between cylinders. You may even have rounded off a couple of cam lobes. It's not a huge job to pull the head and have a look.
 
I agree with the suggestion that you should remove the head. If no water inside then you should be able to repair the engine. I wasted a lot of time and money earlier this year trying to repair an AQ211 (5L V8 but also a variant of the General Motors small block V8) that had filled with salt water. In the end I fitted a remanufactured long block (i.e. with heads) supplied by Keyparts. Early impressions are very good but I only have 20 hours on it. The replacement engine was £1750 plus VAT and came with gaskets and circulation pump. If you decide to fit a remanufactured engine I suggest that you make a note of the block and head casting numbers and give Keyparts a call (they are very helpful and provide excellent service)
 
If you have not done it already try a full wet and dry compression test, it usually shows if its the head gasket or something more serious like a cracked ring or piston.
 
Worth a call to Dave Crawfords, they do all my servicing and are very trustworthy, always do a thorough job. They might have what you need lurking in the workshop.
 
Well i think it all depends on how mechanically minded you are.
Firstly on the positive side the 5.7 V8 is one of the simplest engines on earth. Effectively a Chevy 350 V8 with low profile cams and marinised bits.
So taking the heads off etc is certainly not rocket science. Also these engines are pretty forgiving due to their agricultural nature.
Firstly, dont assume its the head gasket straight away.

Simplest of the Simple, have you checked the dipstick and oil filler caps for mayonaising of the oil?
If it looks like a good dose of mayo then its a good bet the head gasket has gone atleast between oil and waterways.
Then you obviously have to make the judgement call on how much water has got into the oil etc.

If no water in the oil etc then it could be dodgy valves or possibly rings etc or a compression leak between cylinders.
All of which are do-able without NASA knowledge.

I run a smaller 5.0 one so am used to these issues.

If however you really aren't that mechanically minded then before you go any further i would get someone trustworthy to check it out.
There is no reason a good car mechanic couldnt diagnose this issue. Doesn't need specialist marine knowledge.

regards,

Nick
 
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Compression non-existant on Nos. 2&3 on the starboard side

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If you mean the centre two cylinders in one bank then it may be the gasket has gone cylinder to cylinder and there may be no water leak into the bores, have to take the head off to be sure....
 
Thanks for all your replies. Yes it is adjacent cylinders therefore I assumed it was head gasket. Ive checked inside the rocker cover and the dip stick and everthing seems to be the right colour.

One way or another, I need to get the engine out, so Im now booked in next Saturday for an engine lift where I can fully assess the situation. Fingers crossed!
 
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Yes it is adjacent cylinders therefore I assumed it was head gasket.

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Ah but generically head gaskets can blow between:

cylinder to cylinder
cylinder to oilway
cylinder to waterway
oilway to waterway
cylinder to air

(not all possibilities exist on all engines as it depends on the layout of the bores and water/oil ways etc)

If you have compression loss on two adjacent cylinders then it is probably cylinder to cylinder in which case there is probably no water ingress route (and hence no corrosion), and quite possibly it will only be the cost of changing the head gasket itself.

Boat needs to come out if the exhaust arrangement risks flooding depending on what needs removing but it would be much easier surely to just pull the head off in situ rather than pull the whole engine out??? Esp as once the engine is out you'll still need to pull the head off it....
 
I agree.. its possible you may want to have the boat out the water regarding the exhaust manifolds but, on my boat in particular its definitely a 'leave the engine in' to take one of the heads off....

Taking the engine out would just complicate things much further..

I really think under the circumstances, getting a mechanic to look over it for you would be the best course of action.
 
Like he said, oil/water both seem to be right colour/consistency so probably no leak between oil/water ways, so sould be no damage to bearings, etc. No likelyhood of damage to risers/manifolds IMHO either. Get the head off quick - without lifting the engine if possible - and check for signs of scoring/burn between the affected bores. If none, fit new gasket (bolts to correct torque) and sigh with relief it wasn't more expensive!
 
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