CU Engine out! Various problems come to light

Post by **gareth** » 19 Jul 2006, 10:27

Dropped the engine out as have been having trouble with a valve on #3 cylinder. My only mechanical experience has been with this van: following Haynes, reading up loads on here, and with phone support from a family friend who's a very experienced driveway mechanic. Obviously my biggest project to date and it's very nervewracking, but it's basically our only hope as we can't afford to get a garage to do it at the moment.

The van has always had a really oily engine bay, particularly around the fan. This comes back quite quickly after cleaning. The underside of the engine has oil sticking to it but doesn't leave pools in the road. It doesn't actually use that much oil at all, and we check very regularly. Anyway, when I removed the tinwear over the oil cooler I was horrified to find the cooler completely gunged up with oil. The inside of the fan shroud etc is similarly coated. Is this normal? Any ideas what might be causing it?

As I've got the engine out, what other jobs should I be looking at doing at the same time?

cheers
Gareth

1980 2l Aircooled, CU engine

Post by **Grun** » 19 Jul 2006, 12:17

Gareth,
Just looking at a cut away drawing of the type 4 engine, (The CU being a variant) one suspect would be the seal on the front of the crankshaft, behind the fan. There will be plenty of other advice from the more experienced before too long. I only have the old 1600 Aircooled and a 2.1DJ wasserboxer. Seal looks like a spring loaded lip seal just pressed into crankcase, should be easy to change.

Mike

Post by **cumbriankeith** » 19 Jul 2006, 13:33

Gareth - as Grun says it is probably the oil seal but another possible is the oil filler tube. Mine was seeping and causing a right mess. Clean it all up anyway - especially the cooler - take it off and pressure wash it.

Post by **Bowton Lad** » 19 Jul 2006, 15:12

Grun wrote:Gareth,
Just looking at a cut away drawing of the type 4 engine, (The CU being a variant) one suspect would be the seal on the front of the crankshaft, behind the fan.
Mike

According to a VW trained mechanic (Paul at Westhoughton VW-Audi Specialists in Bolton) there is no oil seal at the fan end of a CU A/C engine. However, there is one at the gearbox end.
I always thought that there was an oil seal at the fan end until I accidently
over filled the engine with oil and the excess oil came out behind the fan. It was during a discussion with Paul about this that he said that there is no oil seal at the fan end.

Post by **Grun** » 19 Jul 2006, 16:02

Thanks Bowton Lad,
It is entirely possible that the CU does not have a seal on the crankshaft behind the fan. The 1600 Aircooled I have does not have a crankshaft oil seal at the rear (as installed) of the engine.
But the drawing I have for an early 2 litre Aircooled does show one.

Just proves the 'book of lies' theory

I am begining to think that the the CU engine should carry the suffix NT

At least if it does not have a seal it cannot be defective

Mike

Website · Post by **CovKid** » 19 Jul 2006, 16:25

If you have a full engine gasket set you can replace all these seals. What generally happens is that seals (particularly the old rubber ones) tend to perish enmass with obvious consequences. The thing you MUST check is endfloat.

Grab hold of the fan or put a lever between flywheel and case and see how much fore and aft 'slop' there is. The crucial seal sits behind the flywheel and oil lost here (however small) tends to work its way backwards along the case as you drive around. The oil cooler seals could also be worn out. Other 'possible' sources are the bases of barrels and of course pushrod tubes and rocker gaskets.

The thing to bear in mind is that you can regasket an engine but it won't necessarily have any efect on its lifespan. If it needs a rebuild, it needs a rebuild. Its possible to do it all yourself with patience though - and a heck of a lot cheaper than a new engine.

ChickenKoop and I are rebuilding his CU engine as I speak. Oh and don't be afraid, the VW engine is a very clever yet simple engine. You can guage (to some extent) wear in the bottom end by looking for play (up and down) of conrods on crankshaft (not side to side).

Post by **gareth** » 19 Jul 2006, 19:33

Thanks for all your replies.

Removed the suspect cylinder head today and #3 exhaust valve is quite heavily recessed, so looks like it's time for a new head. At least we were expecting this to be costly!

cumbriankeith: oil filer tube wasn't bolted together so this can't be helping. Another thing for the list! Will dismatle and clean all the oily bits over the next few days - may try for a replacement cooler as it's really such a horrible mess of gunge (not afraid of hard work but this one is grim).

grun: starting to agree with you about the NT suffix

CovKid: Thanks for all this. People telling me not to be afraid is the kind of reassurance I need. Will check for "slop" tomorrow. With my fingers crossed. Rocker cover gaskets definitely need replacing, as do some of the pushrod seals, and a few other gaskets are suspect so it looks like it's worth getting the whole set and having done with it.

Most of the tinwear underneath the engine is missing - would I be right in thinking this has contributed to the problems with the valve? I'll need to start hunting and try and complete the set. Found this link about heat and noise etc - is it worth wrapping the exhaust manifolds to try and reduce heat a bit here?

I'm hoping I won't have the engine out too often so I'm keen to do any little worthwhile jobs now while it's out...

cheers

Gareth

Post by **guz** » 19 Jul 2006, 20:22

number 3 is the one that usually fails
cos it gets the least cooling, tinware and
tinware to body seals all help, if any of
this is missing the cooking is the usual result.

we have a constant cycle of Aircooled
engines being rebuilt up here, we must
be sick in the head, a friend has her
1600 bay engine coming out soon and
i've got a 1600 bug lump half way done
with at least 3 more to do.

oh...you deffo should have a crankshaft
oil seal, if its failed your clutch is buggered
cos its been lubed up nicely.

Post by **Grun** » 19 Jul 2006, 20:42

Guz,
What about t'other end.
Is there a crankshaft seal on fan end or should I delete it from my drawing in the manual?
Please (I won't sleep well until I know

)

Mike

Post by **guz** » 19 Jul 2006, 21:15

i've had a beer and i can't think
straight now (nowt new there)

do you mean between input shaft
and the gearbox ? don't think so.

too hot to sleep anyway.

Post by **cumbriankeith** » 19 Jul 2006, 22:26

There is definitely an oil seal on the fan end of the crank - I have a spare one sitting in my box of bits - GSF list both rear 11726 and front 11729 seals. JK sell them J10451 describing them as: 'This seal fits at the end of the engine nearest the rear bumper'
http://217.29.195.146/FMPro?-db=wproduc ... 32996&-img
Are you convinced yet?

Website · Post by **CovKid** » 20 Jul 2006, 01:02

Just bear in mind (and I mentioned this in another thread on here) that if the bottom end is tired, it often won't take kindly to a rebuilt top end. Its like putting bionic legs on an old lady.

I nearly got sued (or at least they attempted to) by a customer who had oil leaks who insisted I just regasket everything and lap the valves in. I did warn them that the sudden change in pressures could spell trouble and the engine failed within a couple of months. I now refuse to do that kind of work. That said, fine on your own vehicle - just don't waste your time if the bottom end is well worn - its a false economy generally. Lot you can do on a budget though - but do check for wear.

The book "How To Keep Your Volkswagen Alive" is fairly relevant to T25s and written in a very relaxed style but highly informative. The ducting may be different but essentially that block is more or less a beetle engine. I've worked on lots and lots of bug engines over 20 odd years on various budgets. Once all the tinware is removed its a familiar beast then. The best way to go is start with a good crank even if it entails having it reground - for reliability anyway. Don't let this put you off though - you'll learn heaps doing what you're doing.

Valves can go for all kind of reasons but generally symptomatic of an old engine and/or lack of maintenance. Certainly rebuilding your own engine is around half the price of a new one and the best of all YOU built it. Think of it as a fun meccano kit and the job will seem less threatening.

Organising a strip down is a lot easier if you dismantle it in your shed/garage like an exploded drawing - ie keep all the head/rocker stuff together and anything pertaining to left side of engine, keep it on that side of the workshop - makes reassembly a breeze then. Certainly don't just throw all nuts into a big tin - thats a pain. Keep things grouped together.

Post by **Grun** » 20 Jul 2006, 07:24

Cumbriankeith,

Thank you for clearing up the confusion over the crankshaft seal at the REAR (I should have said

) of the crankcase, under the fan.

I did a little research on the web and it is said the 1600 Aircooled still uses the crankcase with no seal, just a flinger disc, while the 2 litre Aircooled uses the "Type 4" crankcase with the seal.

It just seemed a likely hidden leakage point of oil into the cooling air flow, if the bottom end was not to be part of the work undertaken.

Slept quite well despite the heat!!

Mike

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