8v block hex plug

[jackherer 543]

Does this leaking hex plug on the gearbox end of the block unscrew?

 

 

I've never seen one leak there before, is there likely to be corrosion or something or will it just need some thread sealant?

[petert 554]

Yes, it unscrews. Clean up and use Loctite 569 or equivalent.

[jackherer 543]

Thanks Peter, I've got an equivalent hydraulic thread sealant in stock already. The last time I tried to buy a Loctite product (243) it took three attempts before I got one that wasn't an obvious fake!

[petert 554]

Interesting that it's green when there's oil behind it!

[jackherer 543]

Oh really? I assumed it went into the water jacket due to the deposits, there is moisture all over the area too.

 

It's not my car and I must admit I haven't actually checked the colour of its coolant yet so it might not even match!

[petert 554]

It's the oil gallery.

[jackherer 543]

I'll have a closer look tomorrow at the blue/green stuff, maybe it's the remains of some sort of sealant.

 

It's not leaking oil from there though so I wont take it out.

[DamirGTI 327]

Seems to be some kind of seal under that plug :

 

http://www.miamistu.co.uk/pug/GB/205N/0/01C55A.HTM

 

... thus probably "seal swelling" .

 

D

[Tom Fenton 1,526]

Looks like blue hylomar to me. If it isn’t leaking I’d leave it alone.

[jackherer 543]

I've had another look at this and the news is not good.

 

The blue deposits are definitely coolant that has crystallised as it's dried out.

 

It hasn't come from that plug though, there is a crack on the front of the block below the inlet manifold with coolant weeping out.

 

It was able to get from there to behind the flywheel because the gearbox was coming away from the engine and there was a 1-2mm gap.

 

[barneys66 120 1 Cars]

I think I got my money's worth out of that bottle of Radweld 

 

Shame it's opened up again, but thanks @jackherer for what'll hopefully be a more-permanent repair.

 

Think I'd better switch to value beans this month - the jobs are stacking up! 

 

 

[DamirGTI 327]

I'd blame that on such severe OE head bolt torque spec. , just insane amount of torque force for aluminum block .. bolt threads pulling out and cracks down on the block around head bolt hole ends .

 

One of the reasons i stopped using OE head blot torque spec. long time ago ...

 

 

D

[Tom Fenton 1,526]

Don’t agree. It’s partly the age of the blocks now but more so corrosion from the inside weakening the stressed area. A healthy block will take the torque all day long. If it’s not up to the job of the head bolt loads it’s scrap and that’s all there is to it.

[barneys66 120 1 Cars]

Block was fine..

[Telf 222 2 Cars]

I'm with Tom on this , the corrosion on the water jacket at the bottom corners on the 2 engines I stripped recently was severe . No wonder cracks develop.

[DamirGTI 327]

Stripped quite a few of them too during the years ... and have a few of mines , two of them blocks which where 100% mint internal with absolutely no corrosion around the liners/liner base but yet they still cracked horizontally down the head bolt hole ends . Welding was not an option so i had to scrap them just because of the cracks , everything else was spot on . 

 

While the age of the block certainly isn't questionable , nor is the impact on the block metallurgy during all those years of heat-and-cooling cycles , this alone to me suggest altering the head bolt torque as to much and unnecessary from when being new , altering a bit but still enough to made and provide long lasting sealing on the HG . 

 

As far as internal corrosion goes , some blocks (goes for the heads too) are better with regards to this while others are worse not so much the matter of age as i've seen but more due to poor/irregular coolant flush/replacement (good quality antifreeze and distilled water instead of regular tap water) .

 

Also , later blocks (XU7 , and think late XU5 from 406/Xantia too) are better with regards to this "cracking problem" , probably reason being - increased/added reinforced block webbing :

 

Early :

 

 

 

Late :

 

 

 

D

 

 

 

[jackherer 543]

24 minutes ago, DamirGTI said:

 later blocks (XU7 , and think late XU5 from 406/Xantia too)

I think I've asked this on here before but what are the issues you'd encounter if you wanted to use an XU7 block to re-block an XU9JA or an XU9J4? Pretty sure we didn't get XU5 406s or Xantias in the UK.

[SRDT 150]

It looks close but it's not the same spare part number:

 

http://www.miamistu.co.uk/pug/GB/405N/0/01C20A.HTM

 

The XU7JP4 and XU7JB blocks are even worse, you can see on the picture above that there is no way to fit a dipstick on the rear.

[DamirGTI 327]

XU5JP from Xantia (same as XU7JP) :

[DamirGTI 327]

XU7JP4 from 306 :

 

[DamirGTI 327]

Then the late 8v XU5j/XU7j will be direct swap ... 16v J4's might need some work , and use of OE 16v type mount which goes with the block .

 

Think the dipstick shouldn't be a problem on the front on a JP4 with the XU9JA conversion .

 

D

[DamirGTI 327]

[SRDT 150]

Using a XU7JP4 or XU7JB means more work and unlike the XU5/7JP the XU7JB head isn't the same as a GTI one.

As for the XU9J4 block it's the only one with oil squirters unless you can find one from a 205 Turbo 16...