Head gasket

[ahistand]

Just wondering what peoples thoughts are on using Hylomar as a head gasket sealant, like I have seen another parts supplier suggest. Or is it better just to go dry. THis is for a 1.6NA

[tylernt]

On diesels the main problem seems to be leaking compression into the coolant passages. I never seem to hear of oil in the coolant or vice versa without an accompanying compression leak as well. I don't think any gasket sealer is going to stand up to the peak cylinder pressures developed in a compression ignition engine, so, dry should be fine. The one on my car right now is dry.

[84vwrabbitdiesel]

I know anything is possible but... Is it likely that a seeping head gasket could result in elevated levels of oil consumption?

I've had an 84 VW Rabbit with a 1.6 diesel for six months and driven it 1,500 miles. Previous owner indicated it sat unused for quite awhile.

I can't be sure, but she seems to burn quite a bit of oil.

I'm putting new head gasket, oil baffle, glow plugs w/relay, water pump, hoses, timing belt with tensioner and remanufactured fuel injectors / injection pump on my Rabbit this weekend...

Is there any chance something I'm doing will reduce oil consumption to a more realistic level?

[tylernt]

The oil baffle should help.

[84vwrabbitdiesel]

So, it's pretty unlikely that the seeping head gasket is pulling oil on the intake stroke? I know diesels have extremely minimal vacuum... so pushing oil out is much more likely than pulling any oil through the faulty gasket???

Wishful thinking I guess.

Jack says that the cylinders wear in an egg shape and even a motor with 136k could be excessively worn due to extended mileage between oil changes. He also said that reringing such a motor could cause the new rings to break. He also said that any cylinder compression below 375 psi will cause some oil to be burned.

Sounds like a long block is in my not too distant future...

How much oil should these motors burn?

[tylernt]

It's possible the gasket is causing oil to leak out of the engine, but I doubt it would allow oil into the cylinders without also displaying classic signs of gasket death (overpressurized cooling system).

It might be burning oil leaking past the valves... as you say, there is not a lot of vacuum but eventually stem seals will degrade to the point where no vacuum is necessary for them to leak. Thicker oil can help. The seals require some special tools but are quite easy and cheap to replace without removing the engine from the car. Just put each piston to TDC so the valves don't fall down into the cylinder, no rope or compressed air necessary like on a gasser.

My Bunny with 140Kmi burns half a quart of 10W40 in 1,000 miles. Don't know if it's rings or stem seals though. My gasser Fox burns a lot more, and I know it's the stem seals. On a 700mi trip I didn't burn a drop but every morning I get a cloud of blue smoke on startup, so they obviously only leak when cold.

I can tell you that even with the cam oil baffle, I still see a lot of oil in my intake manifold. It may be worthwhile to replumb the breather hose or add an oil separator to help keep the oil where it belongs, in the engine.

I wouldn't worry too much about your engine until after you've addressed all the other possibilities for oil loss and it's still burning large amounts. We're coming up on summer too so even a low compression engine will fire up, you have until winter before you need to do anything drastic.

[84vwrabbitdiesel]

I truely appreciate your input.

That's the crazy thing. Most of the time I've had my Rabbit was during the latest Michigan Winter. This motor starts on the first crank whether it's 75 degrees outside or 10f. I haven't done a compression check but the darn thing doesn't seem to care how cold it is... It just goes!

The valve seals are something I hadn't considered due to the fact that I get little or no smoke during start up. She seems to blow some blue smoke during medium to heavy acceleration though.

Any thoughts?

[tylernt]

That's the crazy thing. Most of the time I've had my Rabbit was during the latest Michigan Winter. This motor starts on the first crank whether it's 75 degrees outside or 10f. I haven't done a compression check but the darn thing doesn't seem to care how cold it is... It just goes!

Sounds like you have good compression then!

The valve seals are something I hadn't considered due to the fact that I get little or no smoke during start up. She seems to blow some blue smoke during medium to heavy acceleration though.

Sounds like breather hose oil to me. High RPM generates more blowby (even a new engine will have blowby) and the blowby blows oil droplets up the breather and into the intake. At extreme levels this can cause runaway. If blowby isn't too bad (and it shouldn't be if you have good winter starts), usually cleaning the screen in the valve cover and adding a cam oil baffle will go a long, long ways to reducing this problem.

[84vwrabbitdiesel]

SWEET!!!

I'll make sure to pay extra attention to the valve cover and its screen while I have it off.

THANKS again.

[rwest1]

Ahistand,

The thread seems to have gone other directions, but regarding your original?

[Just wondering what peoples thoughts are on using Hylomar as a head gasket sealant]

In a perfect world score of threads on VW diesel forums would not relate to head gasket issues (search found 449 on this site). Compression leaks, oil to coolant leaks (they do happen, and fairly often), coolant to daylight leaks, due to failed head gaskets are the bane of old VW diesel users worldwide. All that said, it would seem hard to accept as gospel that VW is the oracle of wisdom in these matters (other than how it relates to making profit). After raking in lots of money on HG related service work through the years, they have upgraded newer units to a more reliable metal head gasket design (a good update for older units where it can be made to work). In my situation I’m mostly dealing with old parts that always have a little twist or warp (though still in spec). Also, this motor has an Al head on an Iron block; Al can have up to 4 times the thermal coefficient of expansion as Iron, which can lead to a lot of dimensional creeping at mating surface. My practice is to always use head studs on my personal vehicles (TTY bolts are used for production cost savings, not because they are the best design for reliability of HG) for compression sealing and long dependable service life. As extra insurance, I also use Hylomar (the stuff is usually still tacky years later if the unit has to be torn down) on both sides of the new HG to minimize the occurrence of coolant & oil leaks. Also, keep your cooling system in top shape; overheating these units can wipe out all your good work in a flash. This has worked well for me, but as you indicate, many advocate other sealers, or going dry!! So… read all the available info (only got 448 threads to go), and make up your own mind. Regards[/quote]

[libbybapa]

I have seen quite a few headgasket leaks such that the engine weeps a small amount of oil around one or more of the oil drain holes. More commonly I have seen significant oil leaks around where the pressurized oil channel goes from block to head. I believe that a sealant could be effective prevention in both cases. I don't think it would do much, if anything, to prevent coolant pressurization from combustion pressure leaks.

Andrew

[tawney]

rwest1 wrote: My practice is to always use head studs on my personal vehicles (TTY bolts are used for production cost savings, not because they are the best design for reliability of HG) for compression sealing and long dependable service life. By TTY do you mean the 12pt. stretch bolts? What exactly do you use instead?

Regarding the Hylomar, (or equivalent,) wouldn't you need to put a thin bead around each coolant and oil passage on both sides of the gasket for it to be effective? If you just put a line of it around the perimeter of the gasket, you would not be minimizing the possibility of the oil-in-the-coolant type leaks. (CoolAirVW has a good discussion and picture of such under "Engine Pull Thread")

[rwest1]

Torque to yield (TTY) is the term and it does refer to factory stretch bolts. Raceware makes studs for 12mm head bolt replacement and also for the older 11mm bolts, but they’re pretty expensive. ARP studs through Summit racing are a lot cheaper. See the URL below for a lot of info on this subject. I’ve seen Hylomar in spray cans, which would probably be the easiest to use. I use the tube and just lay the HG on clean flat surface (plastic surface of card HG came on works), then use a stiff brush to daub a thin coat over entire surface, turn gasket over & repeat. Only touch HG on edges and inspect carefully for any contamination (hairs, whatever) and its ready to install.

http://www.vwdiesel.net/phpBB/viewtopic ... abbe711901

[tylernt]

SWEET!!!

I'll make sure to pay extra attention to the valve cover and its screen while I have it off.

THANKS again.

If your screen is anything like this one I just picked up at the junkyard today, cleaning it will definitely help:



I got it off an '85 gasser Golf, it has the hole instead of the nipple for the breather so I can use an oil separator on it.

[Diesel Dean]

I use copper spray gasket made by Permatex. I dust the gasket on both sides and dust the head and the deck surface. Jack says it's ok to use. I don't know if it's luck or that I use the spray gasket but I never buy new head bolts. I have put many many engine together this way with no leaks. I know it's a major NO NO to re use old head bolts but it's working for me.