Leaking Barrel-Block suspected. Gasket or Gunk to fix??

Hi all

So, rebuilt my Type 4 CU/2lt the other month. Previously had been dry as a bone, and fitted new gasket set all round, but it has picked up some annoying oil leaks in the rebuild.

I've managed to minimise them by
1 - replacing Oil Cooler, which I should have probably done the first time around. A lot less oil in and around the fan so suspect that Oil Cooler ended up leaking from having been manhandled, and replacing has done some good.
2 - refitting pushrod tubes with sealant gunk on smaller/inner ones to seal. Again, seems to have limited oil a bit, but I'm still getting some oil sitting in the further back ones (#2 and #4 cylinder), though suspicion is that is coming from above and sitting in the space.

I'm now suspecting that the remaining oil is actually coming from the cylinder-block joint, as the fins, there are noticeably damp/wet with oil and oil doesn't travel up, right?

Does that sound like a logical assumption, or is there another likely culprit? If so, I'll need to pull the engine and replace I think. Massively annoying and thus I'd like to make sure they don't leak again, so what are folks suggestions for doing it right? I've seen some folk suggest sealants over gaskets.

 

Good to put a smear of sealant like Curil T on the join, just to head off any potential leaks.

 

VW discontinued the paper gaskets if that helps. Yes I know they are provided in the gasket sets.

 

So, any make or supplier recommendations for good quality barrel-block gaskets then?

 

Great, I have some Curil-T knocking about. Do you use it with or without a gasket?

 

Skip the gaskets, and just use sealer.

 

Without is fine. Just a smear.

 

What 'e said. ^ skip the gaskets, use just sealer.

 

Halfords gasket sealant also works. Just a thin layer you dont want blobs orbiting the engine getting ready to block an oil gallery.

 

It depends if you have used head gaskets, the deck height and CR whether you need a spacer shim or not.

VW Technical Bulletin 10-90 T01 states:
Remove the aluminium head gasket.
Remove the paper gasket between the cylinder and crankcase.
Install a 1.6mm aluminium shim at the cylinder base to compensate for removal of the paper gasket and the head gasket.

If you remove the head gasket and the cylinder base gasket but don’t bother with a spacer shim obviously the deck height will be reduced and the CR will be increased.

 

Dry assemble it all, measure the deck height, cylinder head volume, use it to calculate the compression ratio, and then decide how many cylinder gaskets you need .. as too much deck height can lead to hotter running , but too little deck height producing higher compression ratios can also lead to hotter running.

 

I would be inclined to check your head bolt torque. It is not uncommon for the lower bolts in the head to be significantly looser than the tops. I often add an extra 5Nm to the lower bolts when assembling.

Oil through the barrel area is often a sign of excessive crank pressure caused by worn piston rings.

With regards to push rods I just oil the seals and with a twisting action push them in. The twisting action is very important as the O ring can sometimes tear or come out of it's channel slightly. Again cleanliness is key for a good seal. I find push rods mainly leak when people start adding silicone and all other settings sealants.

 

Ta.

New piston rings all round, so hopefully, not that, and all bolts tightened to spec, but I could always overtighten!

re push-rods, I guess this is one when there is competing thoughts, as I've had a professional engine builder tell me to definitely use something like curil-T (non-setting sealant), but various other not to use a sealant at all!! However, are you just warning against sealants that actually sets?

 

Sealant on o-rings.
Generally no but if the sealing surface is pitted you'd be crazy not to use something. Not sure about curil-T for this as it might dissolve away. My builder used Wellseal, it certainly did the job, though it made getting tubes out 15,000 miles later rather difficult. After removing there was a thin green line of o-ring still bonded to the head all round. Of course it did still leak between the o-ring and tube here and there but if he'd glued to that as well I'd have needed a new set of tubes by the time I'd got them out!

When I put them back, just because I had some, I smeared the coroded head end with probably completely unsuitable anaerobic sealant and still left them dry onto the tubes.

If you have new heads it's advisable to soften the very sharp entry particularly at the top where the last inevitably bunched up part of the o-ring enters.

 

I use a smear of O-lube on the O-rings, never any sealant, setting or non-setting. But I make sure the bores that the O-ring fits into are perfect with no grooves or scratches and the lead in chamfers have no burrs.

I only use sealant on metal to metal faces, if there is a gasket, seal or O-ring I don’t use sealant.

 

Thanks @77 Westy . I do find the world of greases, lubes and sealants all a bit confusing. Do you have a maker or brand name of O-lube, as the only one I can find is Parkers O-Lube which seems to be a US product, but I can get it?

Just want to make sure before I shell out for some, then find it's the wrong stuff, which has happened often enough!

 

Curil-T is just fine. It’s German.

 

I use an industrial lube from Gallenkamp that doesn’t seem to be available any more, Red rubber grease should be okay. https://www.ebay.co.uk/itm/red-rubb...137105&hash=item3b4ec2a0ea:g:~ewAAOSwR29ZEu8y

Or Parker O ring lube..https://catalog.barnwell.co.uk/product_info.php/products_id/399

 

Check your head bolts. Fortunately it is only the ones in the cylinder head that become loose. Probably because the bolts are much longer. Torque them back up to the specified 32NM. I like to run a heat cycle and check the cylinder head bolts and the exhaust bolts.

 

Hi all

So, going to attempt to fix leaking cylinder/block this weekend.

Really simple question. In dropping the engine and getting it out, I'll be removing the J-tubes and atleast loosining off the heads. Will I need to replace the exhaust and cyliner/head gasket for new ones, or can I simply reinsert, given I only put them on as part of engine build 2 months back, and the engine has only done about 500 miles?

Always wondered about reusing gaskets in general anyhow.