Understanding how engine died - water on inlet and exhaust sides

[loco]

Hi all, this story goes back a couple years now. I'll try to compress the background as much as possible. Engine is a 4.3L V6 vortec. Raw water cooled.

- had leaky inlet manifold (vacuum leak, not water). Had manual provided by engine supplier for non-vortec model and over-torqued inlet manifold bolts.

- Replaced inlet manifold gaskets myself.

- Still got water in oil. Fair amount of time had passed. Took it to shop. They took engine out, replaced cylinder heads, cleaned out milky oil. Engine made loads of smoke/steam from breathers and sounded hot (ticking when we shut it down, though water temp was OK). Shop said big end bearings must be shot.

-Best part of a year has passed and we have a new long engine to go in. Taking the old engine apart, it looks like it's come up from the seabed, horribly rusted again, and with signs of water on both the inlet and exhaust sides. It's literally had about 2 hours of run time since the top half was rebuilt.

So, from the old engine, I'm only reusing the inlet manifold, carb and ancillaries. The rest is all new.

I'm just worried that the inlet manifold might be damaged, though the engineer says he cleaned it all up and it looked absolutely fine. I've asked them to do a pressure test on the coolant side before he puts the engine back in.

Any other thoughts on why the engine would look like this after having been professionally rebuilt, with new cylinder heads? any other tests I should do before, too? I'm thinking I'll have them run it on a hose for some time too before it goes back in the water and confirm no water appears in the oil.

 

[Scott Danforth]

because it sat with moisture in the oil

 

[Bt Doctur]

that might be true but there is way too much rust in the intake runners , that could be a leaking intake manifold . The valley does not look like it has any rust

 

[Scott Danforth]

Minimal air to valley, however with all the rust under the valve covers, i would be using a brand new intake

 

[loco]

so in thinking about it, my current theory is since there was so much water inside the engine, the breathers were throwing out loads of steam/fumes, and the breathers are connected to the flame arrestor, so when the engine shut down, that moisture would have sat on the inlet side and on the exhaust side.

My concern is I've not seen the 'smoking gun' as to what caused all the issues with the previous engine, so I'm not completely confident with that inlet manifold, despite it looking Ok when inspected. Might be worth pulling apart the old engine some more to find out.

 

[Lou C]

Hi all, this story goes back a couple years now. I'll try to compress the background as much as possible. Engine is a 4.3L V6 vortec. Raw water cooled.

- had leaky inlet manifold (vacuum leak, not water). Had manual provided by engine supplier for non-vortec model and over-torqued inlet manifold bolts.

- Replaced inlet manifold gaskets myself.

- Still got water in oil. Fair amount of time had passed. Took it to shop. They took engine out, replaced cylinder heads, cleaned out milky oil. Engine made loads of smoke/steam from breathers and sounded hot (ticking when we shut it down, though water temp was OK). Shop said big end bearings must be shot.

-Best part of a year has passed and we have a new long engine to go in. Taking the old engine apart, it looks like it's come up from the seabed, horribly rusted again, and with signs of water on both the inlet and exhaust sides. It's literally had about 2 hours of run time since the top half was rebuilt.

So, from the old engine, I'm only reusing the inlet manifold, carb and ancillaries. The rest is all new.

I'm just worried that the inlet manifold might be damaged, though the engineer says he cleaned it all up and it looked absolutely fine. I've asked them to do a pressure test on the coolant side before he puts the engine back in.

Any other thoughts on why the engine would look like this after having been professionally rebuilt, with new cylinder heads? any other tests I should do before, too? I'm thinking I'll have them run it on a hose for some time too before it goes back in the water and confirm no water appears in the oil.

Your story is a little confusing. You say first that you had a vacuum leak, not a water leak, then replaced the intake gaskets then got water in the oil due to over torquing the intake bolts (Vortec is like 10 ft lbs, Pre Vortec is 30 ft lbs if I remember correctly). Then you say you are getting water in the oil which seems like the start of the problems, which seemed to go on for a period of time (water in the oil = rust esp on valve train components) then it went to a shop, got a top end overhaul, and engine made loads of smoke/steam through the breathers. Shop says big end bearings bad which makes no sense. Smoke/steam from breathers suggests leaky head gaskets, cracked heads or block any or all of which will allow water in the oil and you're back to corroding the inside of the engine.
So my take on this is the shop didn't do the job right. There are a number of things that can go wrong, not cleaning the deck of the block carefully, not cleaning out the cyl head bolt holes well so you get accurate torque, not using proper procedure to torque the heads, same thing with the intake manifold as far as cleaning the mating surfaces. Sounds like they botched the job and blamed it on something else, big end bearings would make a knocking noise and/or show low oil pressure not smoke/steam which is a clear sign of continued water in the oil due to blown head gaskets, cracked head or block.
I did the same job on mine, the water was in it for about a week, had the cyl heads checked out and had to replace due to cracks from a previous overheat, put it back together and still running fine 3 years later. Water in the oil you must act fast to get it out and find the cause. BTW I'd probably just get a new intake since they are available for Vortec engines and make sure to use all new exhaust manifolds and elbows. Using old exhaust on a new engine is a bad idea, same reason, water in cyls/oil. The Vortec intake gaskets were problematical, I'd use only the best quality gaskets, and follow torque specs carefully.
What's interesting in your pix is that there seems to be more rust in the intake ports of the intake manifold than in the water ports which are the front and rear most ones. Normally what you see on raw water cooled engines is no rust in the intake ports and rust in the water ports. That suggests water getting in the cyls, either from a bad head gasket replacement job or cyl heads or block deck surface not flat to GM specs (less than .003"). Or even a defective water cooled exhaust, water can leak into cyls from rusted manifolds, elbows, or a bad gasket between the two. Since you're posting this in the V/P section I'm assuming this is a V/P engine with V/P exhaust, and the gaskets on those between the manifold and elbow were also problematical and revised a couple of times. The latest V/P gaskets were much improved and are used with a spray on sealer. Did the shop check the exhaust for leaking when they did the cyl heads? In salt water we change the exhaust at approx 5-7 years, if you see any rust trails coming down from the joint between the manifold and the elbow it could be leaking inside.
When I did mine (OMC engine, originally had OMC one piece batwings, converted to Volvo style exhaust during top end overhaul) I use Barr aftermarket exhaust with Barr gaskets and no leaks.
And this puts the responsibility back on the shop that did the top end overhaul, they should have properly prepped the block deck sealing surface, cleaned out the bolt holes with a thread chaser, and checked both the block and new heads for warpage, and checked the exhaust system.
On the older Pre-Vortec engines, the intake gaskets seem to never leak. Never had a problem with mine ever. I think reducing the # of bolts holding the intake on for Vortec engines was a mistake on GM's part. Pre-Vortec had 4 more bolts. I think better gaskets and following toque specs solved the problem. It was a huge problem on GM vehicles using the Vortec engine for a number of years, especially the mid size Blazer SUV and S-10 pick ups which used this engine in just about all years. Here's mine when taken apart note the lack of rust.....You can see a bit in the cyl heads combustion chamber areas on each one, in one cyl but that's it. Nothing else was rusted and this was in salt water. I actually prefer the older Pre-Vortec engines due to better intake sealing, adjustable valve train and no problems with the timing chain covers leaking (Vortec used both plastic and aluminum covers, that were prone to leaks). Yes they make 20 hp less but I can live with that!