Perkins 4108 problems

"My Perkins 4.108 has become d

"My Perkins 4.108 has become difficult to start, & when it does finally start it is running unevenly, struggles to build up revs & surges back & forth mildly. I have ruled out a fuel problem, new filters have been fitted etc. there seems to be more blue smoke exiting the exhaust. I fear the rings may be shot....has anyone got any ideas? John Hamilton."

"The first thing I would ask i

"The first thing I would ask is the smoke really blue or more white. Generally, the rings will wear at an even rate and cause a general lack of power. You'll get white smoke at idle (low compression) and black smoke at less than full load conditions (unburned fuel). Hard starting will also factor in. Even with these symptoms, the engine usually runs smooth and does not surge. I would start with the simple stuff first. Clean the air inlet screen. Make sure your fuel stop is in the fully retacted position to the mechanical stop (full run position). Double check all fuel supply hoses and fittings including the primary fuel filter gaskets. If this engine gets any air in the fuel it will run like crap. Then remove the valve cover and crank the engine with the fuel stop engaged and observe the valve action. Make sure they are all operating smoothly with no sticking valves. Then renew the injectors with a fresh set. If this doesn't do it, you work your way back to the injection pump. Beyond that you could have burned valves, bad rings, excessive wear etc., all requiring total overhaul. You didn't mention the engine hours or frequency of use, which could be useful in diagnosing the problem. Good luck, Darel."

"I have 11,000 hours on my 4.1

"I have 11,000 hours on my 4.108. If maintain right they will last a long time under the most extreme conditions. Having said that, I had a similar problem a few years ago. After rebuilding the injectors and injection pump the problem was gone. The cause was bad fuel. I picked up diesel fuel at a marina in Pensacola, FL that had been treated with “Valvtect” Fuel Micro biocide. The problem was that they had no idea how much was added and they did not tell me and I added more. It turns out that they used 10 times the recommended amount and it dissolved all off the rubber seals in the injector pump, fuel lines and rest of the fuel system. The rubber turned to mush and plugged the ports and caused excessive corrosion in the pump. The symptoms were as you described. I am not saying that the cause of your problem is the same but the operating condition is. I hope this helps."

"Hi, I own a 4108 M Perkins,

"Hi, I own a 4108 M Perkins,
On the last time i`m rnning out of fuel, without aparently reason.

Did you know, what is the consumption rate , on 1.800 , 2000 , and 2.200 Rpm ?"

You should be using 1/2 to 1 U

You should be using 1/2 to 1 US gal per hour.

"As Daryl says, be sure you ha

"As Daryl says, be sure you have tightened and checked the fuel lines, especially the return lines. I didn't pay attention to the returns thinking they were less important, but this engine routs the returns back through the secondary filter, which means that air goes back through the injector system to cause surges in rpms. After tightening and replacing seals, rpms smoothed right out."

"Perkins 4108 I have just com

"Perkins 4108 I have just completed a major overhaul of hoses seals and pumps. After bleeding the fuel system the engine started and ran well. After stopping and then attempting to restart, it would not start, so I re- bled the system. It started. This pattern has continued. I have checked all connections - they are all tight. Before I did the work on the engine it started very well, with very little throttle.

Note when it is running it runs smoothly with no sign of air in the fuel. Anybody got any ideas?"

"I thought I would update you

"I thought I would update you on fuel line air problem. I eventually solved it by replacing all the rubber fuel line olives. In particularly there were three olives on the return line from the injectors, that when replaced seemed to solve the problem. The olives that I replaced were probably the original, and had become "hard" and had "moved" during the engine overhaul, resulting in an imperfect seal even when tightened to the maximum (note there was no fuel leak, but as my new online buddy Jim tells me that air molecules are smaller than diesel molecules). Moral of the story is to replace all seals and washers particularly when old. I also replaced the copper banjo seals on the secondary fuel filter (one attached to engine) with metal washers that has an inbuilt rubber seals. I am sure that these helped too."

Another update to the above. It turned out that the problem was not on the low pressure side but was a fuel injector pump issue.

Last year I did a lot of work on my engine, and after had trouble starting it. I spent hours looking for air in the low pressure side. The engine would after a while (10 seconds) start when cold but when hot refused to start, without bleeding. Once running it ran and idled well. No significant smoke of any color. Turn the engine off after an hour, and immediately attempt to restart failed.

I spent the whole winter fiddling with the system, and eventually after losing the engine 20 miles from home, did what I should have done and took the fuel injection pump off. It was leaking fuel from the main front seal. (the leak was not visible because the leaking fuel went into the timing gear housing at the front of the engine. Another sympton that I should have picked up was that when bleeding and cracking open the injector line at the injectors and turning the engine it took a long time for fuel to squirt out.

I sent it in for testing. It required new seals and a new head. Interestingly when tested the fuel pressure was low on the injection side, but the cylinders were not damaged- just worn - after 25 years, so that when the fuel and pump heated up the clearances were not tight enough to create the necessary pressure to the injectors. The replaced head solved the problem, and the pump tested out at 100%.

It was not easy to find a good company to do the work, however I found on the internet a company called Oregon Fuel Injection in Eugene. They sell (if in stock) rebuilt 4108 pumps with one year warrantry for $680. Because my pump needed a new head the cost was just over $1,000. The turn round after receiving the pump was two days.

The folks there are very helpful. Telephone # 1-800-452-5055, ask for Mark.

website: http://www.o-f-i.com/

By the way it is not easy to take off the pump. On the inside next to the engine is a bolt that needs a 7/16 allan key, and a very narrow space to get at it. I bought a key ($1.75 - about 3 inches long) and cut the elbow piece off and fitted the longer part to a 3/16 inch socket (epoxied) for a 1/4 inch drive extension. You can use a 3/8 drive, but the space is very tight and a 1/4 inch is better.

Hope this post helps anyone who runs into similar problems. Moral of the story is that the low pressure side is not always the problem!

Dick Grimshaw