Welding a nut on to Cylinder head bolts

[Screwdriver]

I would think those studs are corroded into that head all the way down - I don't think you are going to get that off without a machine shop.

Those bolts will be stuck all the way through the head.

They might actually be waisted. Thicker at the head then narrow down until they widen out into the crankcase female thread.

The big sticking point could be the mating surfaces are welded together with corrosion AND a couple of rotted alignment dowels acting like anchors...

Tricky job.

 

[dobbslc]

What engine is it? Looking at the parts diagram will help to see if those bolts are shouldered like Srcewdriver says.

 

[Ubique]

A quick look at the bolts that have come out will confirm or deny that.
If all the fixings that will come out are out, and the engine will turn over then a few quick spins might provoke the head into loosening - by the sounds of it, it's only corrosion not as mechanical fixing holding it in place.

 

[addjunkie]

A quick look at the bolts that have come out will confirm or deny that.
If all the fixings that will come out are out, and the engine will turn over then a few quick spins might provoke the head into loosening - by the sounds of it, it's only corrosion not as mechanical fixing holding it in place.

Dissimilar metals in a marine environment, but well worth a try.

 

[Bobupndown]

Similar with TD5 injectors, soak & hang from an engine crane overnight - occasionally chain a spare rear axle to the front bumper & repeat...

Maybe I was lucky by when I had a Td5 the injectors popped out easily using just an Allen key to lever them up.

 

[Onoff]

How about putting some tension on the head via "eyebolts" in the spark plug holes etc say a winch / chain block to an overhead point, then heat around the bolts? Coupled with penetrating stuff round the bolts.

 

[Bullet2012]

I think you are all missing the big picture here, it’s a jetski, more annoying than wasps at a picnic.
At least with wasps you can just **** them with a newspaper, newspapers are however ineffective against the waternourne nuisances and shooting them is allegedly illegal.
The only course of action is to push it into a skip preferable after burning it. The ski not the OP.

 

[JOEPRO]

Is the head just that top plate on this engine? (About an inch thick) Or do you need to take the whole aluminium assembly off a block?

Some great suggestions here - I like the puller plate idea and lots of heat and oil

 

[dobbslc]

Looks like a gasket under the head, it also looks like it's got a load of silicone type gunk swished out of the joint...

 

[reb78]

Can't help but wonder how much a new engine is at this point! In my hands this would end up as scrap trying all the suggestions here!

To me it would make most sense to take it to a machine shop with the right tools if it definitely needs saving.

 

[OJCar]

 

[Gareth J]

They don't look all that deep relative to their diameter. While almost certainly corroded most, if not all the way, getting them to part should be doable.

If you have oxy-fuel, try heating the steel bolts as hot as you can get them. Red hot+ Honestly, forget trying to heat the head to expand it around the bolts. Then, when cooled a bit soak in release fluid. And repeat. The dissimilar rates of expansion will help loads to crack the corrosion. While it makes sense logically to try to expand the head around the bolt, you can't here.

While the bolts are very hot, you can then try your welder trick again, the heat already added will help compensate for the low power welder. If the welded on fixture breaks, try again, then again.

Or hope that the heat has annealed the bolts so that they can be die ground or drilled.

You probably ought to do some cost benefit analysis too. Value of machine running to you, cost of replacement head, cost of s/h engine, value of your time + whatever parts will be needed to make it a runner, scrap value etc.

You've a lot if work to get the remaining bolts out, even if it goes well.

 

[Beanwood]

Ok -really off the wall idea- all as above for releasing agents. Check if they are shouldered bolts. Heat for sure then weld on a washer followed by a nut as you will get even more heat in that way. Loving the induction heater option!
How about putting the plugs back in and turn it over- getting a bit of help with some pressure from the cylinders.

 

[Beanwood]

…oh and as above DON’T even think about easy outs. That will end in frustration and a snapped tool to sort out as well.

 

[JOEPRO]

Ok -really off the wall idea- all as above for releasing agents. Check if they are shouldered bolts. Heat for sure then weld on a washer followed by a nut as you will get even more heat in that way. Loving the induction heater option!
How about putting the plugs back in and turn it over- getting a bit of help with some pressure from the cylinders.

Or modify spark plugs and add grease fittings. Then pump both cylinders with grease to push off the head

 

[Screwdriver]

Scrapping the cylinder head by seriously overheating it (aluminium will likely not stand the temperature of red hot steel) is a likely destructive method of removal.

An aluminium casting like that will endure the bolts being heated to red hot quite happily so long as the heating element (like oxy-acetylene) does not play directly on any part.

Meltingpoint of aluminium is circa 660ºC, "red hot" steel is typically 700-800ºC but would only transfer that heat energy via conduction. Aluminium is a very good conductor of heat, plus the very design of the casting is intended to disperse hot spots.

Plus that heat transfer has to be conducted via an assumed film of corrosion which is the entire purpose for this process...

I once had to remove some unbelievably reluctant exhaust studs from an old FireBlade (aluminium cylinder head, steel studs) and I did that by getting them glowing bright cherry red with a stick welder. So hot you could easily bend the stud with a spanner on the welded nut. The stud cools down to a black heat in seconds. No damage to the head or the relatively delicate threads. It's a known good technique.

The issue is of course, not allowing a flame heating process to impinge on the casting. In this case, stick welding will melt the much longer crankcase studs before the length of the stud gets red hot. The plasma of a stick weld is way hotter than the melting point of steel and way hotter than oxy-acet, 10-20 thousand degrees vs. 2-3 thousand.

 

[bricol]

A quick look at the bolts that have come out will confirm or deny that.
If all the fixings that will come out are out, and the engine will turn over then a few quick spins might provoke the head into loosening - by the sounds of it, it's only corrosion not as mechanical fixing holding it in place.

I do like the word "only" . . . steel and aluminium in a damp environment, possibly sea water . . . about the best way to set off galvanic corrosion. Might as well weld them together.

 

[addjunkie]

Or modify spark plugs and add grease fittings. Then pump both cylinders with grease to push off the head

A hydraulic hand pump could possible work, over the grease. Jet skis are almost as irritating as old outboards….Id have run out of patience by now and started battering with a BFH!

 

[reb78]

A hydraulic hand pump could possible work, over the grease. Jet skis are almost as irritating as old outboards….Id have run out of patience by now and started battering with a BFH!

I like the idea but would imagine the grease method will be more likely to push grease past the piston rings in the current scenario?

 

[JOEPRO]

I like the idea but would imagine the grease method will be more likely to push grease past the piston rings in the current scenario?

I know nothing about these things but looks like it may be a 2 stroke so the intake and exhaust ports would pose the more immediate challenge for keeping grease in