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GrowleyMonster · 18-09-2023, 09:09

Quote:

Originally Posted by SailnParadise

Thank you. I didn't realize glow plugs were needed even in warm weather for proper operation. I will check. Do you happen to know their location?

In warm weather a 4-108 should start just fine with no glow plugs. If you want to use ether, disconnect or disable them. Also I prefer to spray the starting fluid on a rag wrapped around the intake, and not spray directly into the intake or air filter. Those are not particularly high compression engines and you could develop pressure spikes that could crack the head or a wrist pin or rod.

Your valves might need adjusting. Get yourself a couple of head gaskets so you got one and a spare. Never re-use the old one even if you get it off in one piece. Check for proper operation and clearance.

Don't just bleed the injector lines. Pull the injectors at least once, and check for a good spray pattern. They might need cleaning or replacing.

Do yourself a big big favor. First of all, buy your filters by the case. By the multiple case. It sounds like you got a lot of crud in the fuel tanks and rough weather stirs up all the goop. A racor 500 is a fine setup for your primary, but install a second one in parallel so you can hot switch them. Install a differential pressure gauge or just a vacuum gauge on each filter housing. When you are getting stopped up, switch to the offline filter and then replace the dirty element. Consider installing a better engine mounted filter, too.

I know a guy with a 4-108 who made a dandy intake air heater out of a 12v blow dryer. There is lots of cool 12v stuff in bigger truck stops. My 4-107, basically same engine except with wet sleeves and smaller head bolts, has neither intake heater nor glow plugs. I can usually get a start just fine even in winter, and only rarely need ether. However, I do cheat a bit, with an electric fuel pump at the tank, which bumps up the pressure head at the primary filter to about 5psig. It is a huge help for bleeding/priming the system and I think it cost maybe $12 or so. Naturally at that price I got a spare. Once I got the engine running I can shut off the electric pump.

Got a spare starter? If you keep leaning on the start button, sooner or later you will burn up the starter. Check all your connections for corrosion, too. Bigger wires never go out of style. I run 2/0 silicone jacketed welding cable and crimped terminal lugs. Probably not ABYC compliant, but it is not too expensive, and is very easy to work with. Check water level and specific gravity in the batteries, too. You might think you are spinning the engine good, but actually not. You want as much starting power as you can get.

When you get the boat to a slip, do a compression test, if she is still a difficult start. Observe your exhaust, too. It should be nearly colorless once it is up to normal operating temp, and not too smokey even after it runs for just a minute. A healthy 4-108 won't smoke much at all.

A lot of installations have all sorts of pressure and temp switches that close a fuel valve solenoid, and sometimes there is more than one solenoid. Hand-over-hand your start circuit and your fuel system, make sure there are no surprises.

rpackard · 19-09-2023, 00:40

As said, 4-108s don't have glow plugs but SOME have a heater in the air input. These are old engines and often the compression is very low. Starter fluid like ether will get it going . Or, if there is a heater in the air intake, you need to know how to use it. For that, there will be a button someplace that you push for about 15 seconds to get the heater red hot. Then when you hit the starter some fuel drips on the heater, bursts into flame and is sucked into the engine and it starts. But ether will do the same thing. I had to use theater for the first start each day when cruising in SE Alaska.

Tighten all the fuel connections. If you have a very small air leak the first start each day is even harder.

Redcoat · 19-09-2023, 14:11

10mm bolt on the side of your injection pump. Take it out and bleed the pump with clean diesel. Buy lots of filters for your Racor. Because the tank is full of crap and when got to sea it stirred it all up.that part of your pump is full of it. Clean it and go through the bleed process for the injectors. Hope it helps.
Redcoat