Starting engine with no intake manifold

[marksae]

I just overhauled my whole cooling system, including changing the heater hoses. Upon startup, it looks like I have a water leak coming from the firewall area. I would like to start my engine with the intake manifold removed to pinpoint where the leak is coming from.

Is it safe to do so? The three hoses (1 on top and 2 on bottom) that connect to the intake manifold are disconnected. I have the lower CCV hose still attached to the manifold. Should I reattach that one to the oil pan? It looks like it has a check valve on it. What about the other two hoses? I don't want to have an oily mess in the engine bay!

[sapote]

I just overhauled my whole cooling system, including changing the heater hoses. Upon startup, it looks like I have a water leak coming from the firewall area. I would like to start my engine with the intake manifold removed to pinpoint where the leak is coming from.

Is it safe to do so? The three hoses (1 on top and 2 on bottom) that connect to the intake manifold are disconnected. I have the lower CCV hose still attached to the manifold. Should I reattach that one to the oil pan? It looks like it has a check valve on it. What about the other two hoses? I don't want to have an oily mess in the engine bay!

With no manifold connected, how does the DME meter the air for the correct mixture? No way.
To check for coolant leak, go to O'Reilly auto parts and rent a pressure test kit including pump and adapter cap then pump it to 20 psi and watch for leak.

[marksae]

With no manifold connected, how does the DME meter the air for the correct mixture? No way.
To check for coolant leak, go to O'Reilly auto parts and rent a pressure test kit including pump and adapter cap then pump it to 20 psi and watch for leak.

Okay, pressure testing the cooling system seems like a much better option. Does O'Reilly tester have a BMW adapter? I assume you attach it to the expansion tank cap?

[ClevoCapri]

You can idle the car with no intake . It will throw codes but will be fine if you dont want to buy a cooling system pressure tester.

[maupineda]

It will run, but will leave codes back. I would not be sure if the engine light will go away on its own or you need to clear it with a scanner

[R1pilot]

Get the pressure tester from Harbor Freight. It has the BMW adapter and yes, you hook it up to the overflow.

You will find the leak quickly.

[sapote]

The kit has the correct threaded cap adapter; I had used it before. It’s free.

[marksae]

Thanks for the suggestions. I rented a coolant system pressure tester from O'Reilly and found the leak. Troubleshooting this was much easier with this tester vs trying to fire up the engine with everything disassembled.

I must've rolled or pinched the o-ring inside one of the heater hose plastic connectors. I pressurized the system to 13 psi, wiggled the connector and it leaked quite a bit. I ended up removing the hose, and removing/reinstalling the o-ring. I pressurized the system the same way, and now that connector no longer leaks when I wiggle the connector the same way. Hopefully it doesn't leak after I put everything back together.

[sapote]

I must've rolled or pinched the o-ring inside one of the heater hose plastic connectors.

Did you use any silicone grease (or brake grease) to lube the O-ring and its mating surface? Need to do this to avoid damaging the O-rings.

[marksae]

Did you use any silicone grease (or brake grease) to lube the O-ring and its mating surface? Need to do this to avoid damaging the O-rings.

I should have used grease. I didn't though. This time, I just used coolant as the o-ring lube. I also wiped the o-ring mating surface on the engine side real good. It might have been a little dirty. I'll be sure to lube the o-rings next time.

[sapote]

Not just for this application, all hydraulic application O-ring must be lubed with grease or the friction surface will damage it.

[ClevoCapri]

A wipe of coolant on the oring is perfectly fine. No need to overthink this stuff!