Intake removal questons

[apfrancis]

So I need to remove my intake system to replace the intake manifold gaskets. I have already ordered the head gasket kit from autohaus. Can anyone help with a list of while-i'm-there items that are much easier with the intake removed? I can think of maybe fuel and cooling lines (help with diameter would be appreciated!) Is there a cleaning/service I can perform on the injectors while they are removed? I have a fairly limited time-frame to complete the project, and would like to compile as many parts as possible before work begins.

I also plan on doing a compression test to make sure that I don't need to service the cylinder head as well. Are there other things besides the compression test that would indicate a cylinder head problem? (The oil does not appear to contain water). My main concern is that perhaps the manifold gaskets failed because of a warp/overheating issue. Can a compression test determine this? Thanks in advance for your help!

Andrew

[stewart in slc]

The fuel lines from the fuel rail to the injectors are soft lines and can split/leak. I'd look into replacing those as well.

[T.Hanson]

You can visit realoem.com to see exploded views of the parts (gaskets) involved.

Removing the intake log is not difficult but fairly involved. As far as, " While you're in there," you'll be pretty far, or able to access quite a few things. It will be your call which to renew, or leave alone.

Check the FAQ's for everything from throttle body tune up to replacing the injector fuel lines. If you don't have a second car to cheat from, do take the time to take photos and bag up the hardware, or return fasteners to where they should be until reassembly. It doesn't take but a few hours to forget how things go.

I second the motion to replace the injector fuel lines, O rings. See FAQ for tricks, and use BMW OEM high pressure fuel line.

If the car runs you can look for white smoke on start up, oil smoke on hard acceleration and check the spark plugs besides the compression test to determine the health of the head, seals, valves.

[Mike W.]

I've only seen intake manifold gaskets fail due to being molested, head gaskets will fail a long time before the intake if it's overheated and you warp the head.

As far as things to do while you're in there, first, most important if you're pulling the head, check it for flatness and for cracks. Look over the FAQ, they crack between the exhaust valve seat and the water jacket. If they crack and you keep them full of water so they don't overheat, you don't get water in the oil, you just lose coolant. If that's ok, replace the fuel lines with BMW fuel line, it's not that expensive compared to other FI fuel line and it's good stuff. Both the long ones, the supply to the back of the fuel rail and the return to the FPR. And if you don't know when or if it was replaced, I'd do the heater hose off the back of the head, it gets the hottest water, so it has a shorter life. And it will never be easier to replace than now.

[gautoatx]

Once you have the intake off, the most important ‘other’ items to pay attention too are the rubber components. We strongly recommend that you replace all the heater (coolant) lines. These rot with age from the inside out and are very difficult to access with the intake on. You can tell they need replacing by squeezing them and seeing how soft the rubber is. Additionally, on these older BMW 5-series engines, replacing other rubber such as vacuum lines and the fuel lines that you identified would be a really good idea.

Unrelated to the rubber items, we recommend that you replace all injectors on the 5-series E12. Our experience is that we have found a lot of issue with injectors being clogged and having a poor spray pattern. These really can not be effectively cleaned.

If you have overheated this engine, you should inspect the health of the cylinder head. There are some simple chemical test kits that you can get at your local parts store that will detect exhaust in the coolant (most common on these engines if the head gasket fails). Still check the oil carefully and cut the oil filter to ensure no signs of metallic material or coolant in the oil (milky residue).

[Blaise]

Also, check out the coolant steel pipe that lives directly under the intake. It is prone to internal corrosion. On my 1980 car, it was so thin that it would have sprung a leak within a short time.

Here are a bunch of photos from when I did the same thing. A year later, I pulled the motor and swapped in a 3.5L. I guess it was just practice work for what came later:)

https://picasaweb.google.com/1030509870 ... directlink

[Jeff Dennis]

A compression test tells you health of the cylinders and pistons you need a leak down test to check the valve train.

You can order the correct metric fuel line from Autohaus AZ also. I just ordered it and it works the best that I have found.