Re: My ntakes sealed well with Hylomar (archive)

I agree regarding using permatex products to seal older gaskets insteady of replacing them. In fact, when I first got my car I had a leak in the passenger's side bank of cylinders. Not a big leak, that pesky leak that only shows up when the engine is cold. At the time I was not brave enough to rip the intakes off to try to fix it. Instead I thinned a little permatex high-tack with some lacquer thinner and filled a syringe with the corn-syrup consistency goo. I warmed up the engine and, using the syringe with a 6" rubber tube on the end of it, pumped the thin high tack around the intake gasket. With the engine warm, the lacquer thinner evaporated quickly and the high-tack set in place around the manifold. Presto, I got 17" of vacuum on both banks at startup... no leak... total cost... $3. Ran that way for 3 years until I had to rip the top end apart for something else.

Hennka

I removed my 750iL intake manifolds to replace the valve cover gaskets and paint the valve covers and intake manifolds.

The gaskets (which are very expensive) were in good condition. I really don't like the fact that they bolt to the cylinder head and then the intake manifolds bolt to them. What kind of design is that? I would rather have my intake manifolds bolt directly to the cylinder head, with the manifold gasket squished in between. Normal gaskets cost a few dollars. These cost a few hundred!

I used Permatex Hylomar sealant, a great thick gooey blue compound that seals very well and stays soft. You put it on both surfaces and then bolt together. They have it at Auto Zone and other auto parts stores, about $4 a tube.

Unfortunately, I completely totally forgot to tighten the top row of nuts on one of the manifolds and had a major vacuum leak.

This lead to a lean mixture and caused me to replace my oxygen sensors, which were good, and ultrasonically clean and individually test my fuel injectors, disassemble and clean my DK throttles, (which you are not supposed to do) and repeatedly test every input to each ECM and the EML.

It took me about 4 weeks to discover that this was the problem. It drove me nuts.

I tightened the bottom nuts first, because they are by far the most difficult to get to, and completely forgot the top ones. They weren't even hand tight.

If you want to save money, and your intake manifold gaskets are still flexible (mine were), I would recommend trying Hylomar, and making sure your nuts are tight. If you want to do it right, get new gaskets, and still use Hylomar.

Rick 1990 750iL

I used to have a mint 1988 316 1.8 that I really loved. It had 125,000 km (77,000miles) when I bought it and it suffered from crazy idle ranging between 500 and 1500 rpm.

What the dealer did NOT know and what I myself found out from quite another source was that this car was supposed to have the thick rubber seal under the carburettor (yep last year and last model of carburetted Bimmers) changed at every 80,000km. This had naturally not been done, the stealer had no idea such part existed and many 316 1.8 Bimmers I've seen have had the same problem, including the one POS my wife drives now.

WHAT IF the M70 engine (750i 5-litre V12) has a similar issue? What if you're SUPPOSED to change the intake manifold rubbel seals (is there one?) or gaskets every 80,000 or 100,000 or 150,000 km? (50,000 or 100,000 miles about) What if this information ALSO has not been told to the dealers - or they have but no one remembers it and none of us have taken our cars there for years - and thus the cars have not been serviced right concerning this issue?

What if you're supposed to tighten them every X km or something? I know the engine was designed to be very quiet so a lot of anti-vibration and anti-noise materials/design was used, such as the plastic cover thingy on top of the intake manifolds, could it be there are "too" soft seals/gaskets to prevent vibration and you're therefore supposed to tighten/replace them every now and then?

Those of you lucky enough to have already received their Bentleys (what the heck is wrong with those guys at zigmunt's???); is there a list of periodical services? are the intakes metioned anywhere?

Henkka
leaking like someone shot holes in the intake manifolds :-)

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