Oil Sight Glass M18x1.5

Sight glass 420181 is a plastic plug with a built-in inspection window, screwed into the M18×1.5 bore of the Kranzle pressure washer pump housing. The transparent or semi-transparent plastic body allows visual oil level checking without unscrewing the plug – simply look at the sight glass and read the level through the housing material. It eliminates the need for periodic unscrewing and dipstick operation as required with the standard dipstick cap 40463.

Application

The sight glass is screwed into the oil check bore in the pump crankcase housing in place of the standard opaque plug. The oil level is visible through the plastic body of the sight glass with the pump cold, before start-up – or at any time without interrupting operation. The plastic material of the sight glass is resistant to gear oil and the pump's operating temperature, but is more susceptible to mechanical impacts than the metal dipstick cap.

Used as a replacement for the standard cap when simplified daily oil level checking is desired, or as a replacement for a damaged sight glass when cracked or when transparency is lost.

Symptoms – when to replace

• Cracking or crumbling of the plastic body – the sight glass no longer seals the bore and risks oil leakage during pump operation.
• Loss of transparency – the sight glass has turned white or brown after prolonged use in contact with oil and under varying temperatures; the level can no longer be read.
• Oil leak at the M18×1.5 thread – damaged thread or sight glass seal.
• Mechanical damage to the thread in the plug – difficulty screwing in or out without tools, particularly when the plastic body deforms under tightening.

How to select the right part

Identify by reference number 420181 and thread M18×1.5. The M18×1.5 thread is specific – before ordering, confirm the pitch (1.5mm) on the removed component, to avoid confusion with M18×1 or other M18 sizes used in different pump components.

Sight glass 420181 and dipstick cap 40463 are two different oil level monitoring solutions for Kranzle pumps – they may have different threads or fit different bores. Before ordering the sight glass, confirm that the M18×1.5 thread matches the bore in your pump by measuring or comparing with the removed component.

When fitting the plastic sight glass, do not overtighten – plastic is more susceptible to cracking at excessive torque than a metal cap. Tighten by hand to resistance, without a long-handled wrench.

Compatibility

Oil sight glass for Kranzle pressure washer pumps with an M18×1.5 check bore. Verify the exact compatibility range by reference number 420181 and thread M18×1.5.