Tech Tip #124: How to Time a Perkins Engine

Dr. Diesel
Written by Dr. Diesel


All you need to know about how to time a Perkins engine

This Tech Tip, one in a series we publish, can be used to assist you in timing your Perkins engine, models 4.108, 4.236, 4.248 and the Perkins 6.354. Certain measures need to be taken when removing the fuel injection pump as well installing it.

This Tech Tip follows earlier ones including:

We stock both new and remanufactured Perkins fuel injection pumps. If you purchase one of our pumps it is timed initially and as long as your engine is on Top Dead Center (TDC) when you remove your old pump, our new pump is ready to install.

This Tech Tip though is for people who sent their pump out for rebuilding locally and the pump rebuilder did not set the pump at TDC.  Please note that the Perkins 4.108 and 4.236/6.354 engines do not have provisions to lock the injection pump at TDC. The injection pumps on the new Perkins 1000 Series engines can be locked at TDC.


First, before removing the injection pump make sure you can still see the scribe mark that Perkins put on the engine block. This can be found on the engine block just under the injection pump flange. Having a hard time finding this mark? Locate the other scribe mark on the ear of the injection pump (there are three mounting ears; the mark should be on the one facing away from the engine). If you do not find this scribe mark on the block than make your own using a knife or other sharp object. The two lines or scribe marks should be in line with each other. This will truly save you a huge headache later on when installing the new or remanufactured injection pump.

Next in , unbolt the three mounting bolts that hold the pump on to the block. If you’re working with the Perkins 4.108 marine, 6.354.0 or 6.354.4 marine or industrial the pump will slide straight back and the removal will take no time at all. If you are working with a later Perkins 4.108 industrial or a 4.107 or 4.108 Westerbeke marine engine one extra step will be necessary (these engines use a Lucas mechanical pump). See note below if you have one of the later engines mentioned above.

Note: If you’re working with one of the above models; you must remove the inspection cover located on the face of the timing cover before you time a perkins engine. Inside you will find a three bolt hub that connects the injection pump to the drive gear. You must remove the three bolts before you proceed with the removal. One extra thing: stuff a rag in the cavity between the drive gear and the timing cover. It’s easy to drop one of these bolts into the crankcase.


Once you have your remanufactured pump from Foley Engines you’re ready to install. Locate the splined input shaft on the replacement pump. This splined shaft will have two splines on it which are either siamesed together or in some case one of the splines will be missing. This makes the pump shaft go into the drive hub (mounted on the injection pump drive gear) one way only.

Next to time a Perkins engine, once the pump is in, hand tighten the three bolts that mount the pump to the engine. Here comes the most important part. The two scribe marks (one on the pump flange, the other on the block) have to be lined up to look like one line (perfectly in-line with each other). This times the engine. Finally, tighten the three bolts to lock the pump in position.

If you have one of the engines noted in the removal section (a 4.108 or 4.107 industrial engine or a 4.108 Westerbeke marine engine (sometimes called a Westerbeke W40)): you need to re-install the three bolts in the drive hub (make sure you keep that rag in the timing cover!).

At this point, the pump is back on, the scribe marks are lined up to time the engine and you are ready to put the fuel lines back on and bleed the system.

For more information on how to bleed the fuel system, check out:

Please call us toll free at 800.233.6539 with any questions or to order a Perkins fuel injection pump.

P.S. Speaking of bleeding a Perkins diesel, we have a new spin-on filter kit to replace the hard-to-bleed cartridge-style secondary fuel filter. This spin-on kit comes with a glass Racor filter with a drain valve. Unlike the cartridge filter, you can fill it full of fuel and it makes bleeding the system much easier.

See Tech Tip #112: Spin-on Fuel Filters for Perkins Diesels for more information.

Shop our online store for these popular Perkins products:


Dr. Diesel
Written by Dr. Diesel
Knowledge is power. Power to build ties to engine users. To build a relationship with our customers, we share with you our 105 years of knowledge in many ways. We have this special section called “Ask Dr. Diesel™” where you can pose questions about engines, transmissions, industrial hand clutches, exhaust scrubbers, etc.