6.2 splashing from the intake when cold

Hello everyone!

A brief reflection on my diagnosis please.
A colleague of mine has an H1 with the classic 6.2 that I am looking after.
If the car stands still for a long time and is cold, you can hear it "knocking back" from the intake. No abnormal rattling or mechanical noises.
The car has been driven very little in recent years and has always been parked a lot. I changed the oil a year ago, not 500mi ago.
As soon as you drive the car a bit and/or the oil comes up to temperature, the back-patting from the intake is gone.

My guess. An inlet valve is not closing properly.
In my opinion, this can only be due to the hydro.

I would now change the oil again as a quick&dirty method. Together with two bottles of oil flushing.
I don't know if this is known in the US. This is more or less an oil thinner with the aim of washing out everything that has accumulated. Add it and let the warm engine run for another 20 minutes. Then get out the hot soup!

If that doesn't help. Open the top and take a tentative look inside.

Am I missing something?

By hydro you mean hydraulic lifter? Sure they can make noise but not out of the intake that I am aware of. Usually popping noise in the intake manifold is due to a valve issue.

Go run it hard….long term sitting is not good for motors.

frauhansen said:

My guess. An inlet valve is not closing properly.
In my opinion, this can only be due to the hydro.

Click to expand...

On low-mileage engines, exhaust valves tend to stick in their guides because they have seals. While sitting, oil won't easily migrate in there like it does on the intake valves, which are not sealed.
A stuck valve can cause the pushrod to bend and eventually slip off of the rocker arm. Even end with the lifter coming apart after popping its retaining clip (!)

I would first try to identify the suspicious cylinder, then remove that valve cover and inspect all related parts.

RWH, one of the most experienced, has said run the engine hard.

I would suggest also change the oil. Winter is coming so try lower viscosity.