PTFE Tape on engine bolts?

[Maf]

I’ve had a lot of problems with water ingress into the oil on a 4.3 Volvo Penta. It’s been worked on by someone who’s failed to solve the problem. When the heads were taken off today, the engine bolts had PTFE tape around them. I’ve been told that tape shouldn’t have been used and a marine liquid sealant should have been used instead. Can anyone confirm this and could the tape be part of the problem if it hasn’t sealed the bolts properly?

 

[Momac]

I am no expert but why would anything be required on the cylinder head bolts/ studs ?

 

[Andy Cox]

The cylinder head bolts in the V6 GM units should be fitted dry.
I wonder if one of the heads is cracked and that is how water is getting in. Did he have the heads pressure tested?

 

[Maf]

I’m certainly no expert either and have no idea why there needs to be sealant on the head bolts. The Seloc service manual ( think they’re like Haynes manuals) says “clean and coat head bolts with sealant” and searching other forums I have come across advice on the type of sealant to use. The guy who last worked on my engine has used what appears to be plumbers tape.

The heads have now gone off for pressure testing. I’ve spent £6K with this other guy, my boats been out of service for a whole year and I seem to be back at square one - water in the oil and a boat I can’t use.

I’m looking to take him to court to recover some of my money and just trying to work out what he has and hasn’t done and what he’s done wrong (or possible right).

 

[Portofino]

No expert either but keen classic car enthusiast.
With Alloy heads and / or alloy blocks that have steel liners the head bolts are obviously super strong steel .
Aluminium alloy and steel head bolts + water and you have over time the recipes for galvanic corrosion of the alloy parts , they “ glue “ together or the head bolts just won’t shift , apply excess force and they snap in situ .
Any dissimilar metals even steel / steel vs head bolts there’s less of a risk compared to alloy / alloy / vs steel bolts , but nether the less there’s a risk especially if as said years of hidden seepage in old engines .

Where’s the water come from ? I hear you ask .

Well the head gaskets can seep just a bit sos water reaches a head stud and travels the length of the stud , seeps it’s way along etc , but doesn’t leak out completely asymptomatic.
You don’t know the head bolts are ceased and the head and block have galvanically “glued “ until you attempt to remove .
Say to electively to do a top end rebuild.

It’s not unknown for specialist engine rebuilders to use custom jigs and pullers and take upwards of a week of gradually , bit by bit , day by day by pulling and using anticease agents to eventually pry the head(s) of a block or loosen ceased head bolts .
That’s factored in the workshop time charged out .Its a huge variable , from they pop straight off to 10 days in the jig ?

Somebody’s who unfamiliar with this galvanic “ glue “ phenomena, in a rush , bit heavy handed not use a proper puller gig for that engine - then get it wrong it’s possible to crack some thing even only a micro crack in or near the head bolt channel is enough. You need the proper jig to distribute the forces and protect the weaker parts .

You don’t need any PTFE tape for water tightness of head bolts at reassembly if there are no cracks , warps and the correct gasket kit is used .
New head bolts yes as they are designed ( well the best engine designers :encouragement: ) to stretch in a slight elastic way .Thats why you go back after [ insert short time ] after a rebuild and re torque them up to spec .

It’s bad form to reuse them as they will be stretched out and have lost the initial elasticity.

Speculating maybe the PTFE tape is cheap trick to facilitate reusing the permanently stretched and a tiny smaller dia head bolts ??

Engine rebuilders are like surgeons, you need to find one who knows his onions you can trust .

My 0.02 p s worth

 

[Beamishken]

In 40 years building engines I've never used anything on head bolts apart from a little oil. I've built a few gmv8s and done the same no idea why it would recommend a sealant. Id check the proper manual not the aftermarket one.
If a sealant was required to reduce the chance of seizure then id expect an anaerobic sealant certainly not ptfe tape.
The v6 & v8 chevy engines are usually bullet proof but being raw water cooled suffer from internal corrosion and cracks, usually spots are under the inlet manifold which gives the symptoms you have. The other common place is under the exhaust manifold but that leaks water into the boat. Heads can suffer from corrosion thinning of the galleries causing problems of gasket sealing. The exhaust manifolds can also pass water into the cylinders which eventualy finds its way into the sump but usually causes other issues too.
For 6k you could have replaced your complete long block.
If you want to go to court then you will need a specialist engineers report to identify the issue it will cost but gives a better chance of success
Good luck with it

 

[Maf]

Thank you all for taking the time and effort to reply - it’s much appreciated.
Now the heads are off there appears to be a damaged gasket on the intake manifold and, having had the heads looked at, they are reported to be warped.