Perkins 4-108 overheating

[Lepke]

I've rebuilt several 4108s in business. It should never overheat with an oversize exchanger. A common problem in overheating is not having a good rust inhibitor in the coolant or using water only. Rust forms flakes on the water jackets and insulates them from properly transferring cylinder heat. A flush with a good brand of flush known for it's rust dissolving properties usually fixes the problem. I use Rydlyme because it does a good job dissolving rust, is biodegradable and can be disposed of anywhere. Usually legal to dump over the side. I've fixed many overheat problems by using Rydlyme on the coolant side after other yards failed to solve the problem. Best way is to run the engine for several hours at normal temp, maybe at idle in your case and Rydlyme probably at near full strength.

4108 is rated at 3000 continuous and 4000 pleasure. Engines run at 3000 last a lot longer between rebuilds. I have a 1972 4108 running a 14kw generator. I inspect the impeller yearly and change every 5 years. I grease the housing each time I pull the impeller. At 5 years the impeller is still in good condition but the engine runs at 1800.