The V8 Owners Forum -

Just out of interest how is a pressure test done.

Do they bolt anything to the block. or is it all clamped.

I think some of you can work out where I'm going.

You would have to bolt plates to the top of the block to seal it - and likewise a plate to the front and then pressurise.

You cant clamp it down on a plate like a head or an inline 4 becasue of the head angles

Makes you wonder in your case if some numpty used metric bolts - be good to go along and see if an M10/12 now fits in the treads for the UNC's

Cheers

Andrew

Just be aware following hope the info helps

Blanking plates are used with a pressure gauge (accurate one)

Find out what pressure they intend to use

My local engine builder who is very good pressurises to 50psi, just hold that thought

I had a porous block - suspected, (did actually) but wanted confirmation before fitting top hats, my usual engine builder was unable to fit top hat liners, so used another reputable company local to me.

They pressurised the block to 120psi, pressure would decay to 80psi over night, but were unable to identify the source of the leak. But would hold 80psi OK no decay

Did this several times, no source located, I took over a large bath to enable the pressurised block to be submerged in water, again tested several times, immersed, no visible leaks seen, pressure dropped to 80psi

As the engine was now covered in soap, etc, they pressurised the block and then put it in the hot wash as a last resort!:shock: one of the lads opened the door to put some additional components in, and noticed some bubbles around No 3 liner (the suspected liner!!!)

On confirmation, I had top hat liners fitted, and had some issues, but thats another story, on the forum!!

If I had a pressure test done by my 1st company, they would have told me it was OK --- and they would have been WRONG

Been there and done it the HARD way

Hope the info helps

Pressurizing the block to 120 psi could be a bit dangerous, if a core plug or the block itself lets go it could do you some damage!

I guess its OK if someone else is doing while you watch from a distance

Then again I guess you would have never found the dodgy liner at a lower pressure


Pete

a pressure test done properly is not dangerous, you do it Hydrolically ie. with absolutly no air in the system, that way if it lets go there is no head of pressure to push anything in any direction. I've seen a boiler done to 250 PSI that had a leak, little dribble from a pipejoint (and you use boiled water!!)
Mike

kiwicar wrote:a pressure test done properly is not dangerous, you do it Hydrolically ie. with absolutly no air in the system, that way if it lets go there is no head of pressure to push anything in any direction. I've seen a boiler done to 250 PSI that had a leak, little dribble from a pipejoint (and you use boiled water!!)
Mike

I agree, using liquid is fine, using air could be dangerous.

Pete

Darkspeed wrote:You would have to bolt plates to the top of the block to seal it - and likewise a plate to the front and then pressurise.

You cant clamp it down on a plate like a head or an inline 4 becasue of the head angles

Makes you wonder in your case if some numpty used metric bolts - be good to go along and see if an M10/12 now fits in the treads for the UNC's

Cheers

Andrew

So if they had to bolt a plate to the head, they should have noticed at that point the threads was no good. as the 1st thing they did was a presure test. unless they dammaged the threads when they did this.

hi Leigh
as was said above, sounds like they used metric bolts for the pressure test, it would also explain whyALL the head threads were dammaged at the same time
Mike

thinking about it I would check they have helicoiled the block for the right threads, because if they haven't you are looking at a custom set of head studs.
Mike

kiwicar wrote:thinking about it I would check they have helicoiled the block for the right threads, because if they haven't you are looking at a custom set of head studs.
Mike

As said I would not let them do anthing else as don't trust them. also not going to pay them £235 to fit them. seeing as they are bunch of muppets.

If there are metric there will be trouble.

Also I know a few was good, because a made a piston stop to remove the crank pulley.

Just thought I'd post a couple of pics of my porous liner, well what was left after it was machined out

The bad side


The not so bad side


All fixed now