Submerged engine in river crossing. Idle is now jittery.

[LeighMc]

So, I have a 1998 Delica L300, short wheel base, automatic.

I was driving in New Zealand and had to ford several rivers. Engine definitely had a few dips as water came in out of the engine compartment under the front seats.

Everything was running fine but later that day, after parking, the engine had really low power starting, the dash lights would dim and light back up. RPM's were all over the place.

Parked for the night, next morning it started fine. Assumed something was wet and had dried out. But since then it's developed this issue were it will start fine in the morning but then after about 5 minutes the RPM's when idling slowly start to drop off from about 1500 RPMs down to 400 RPMs when the engine starts to shake like it wants to shut down.

I'm aware I got away pretty lucky right now. Engine could have been thrashed and maybe it's now on it's way.

Not sure what I should start troubleshooting first? I've done some research online but it's all pretty general and not specific to a japanese delica from the 90's.

Spark Plugs? Air Filter? Water in the engine? Water in one or all of the oils?

Any advice would be really appreciated.

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[Growlerbearnz]

If the engine didn't actually stall while underwater you're probably going to be ok. If it stalled, it's potentially a bit worse.

An L300 (especially a petrol one) is fairly generic mechanically, so most advice about curing a wet engine will be relevant.

Seeing as it's petrol I'm thinking you have water in your distributor, which settles to the bottom overnight (allowing easy starting) but moves towards the high tension sparky bits when the engine's running and hot. I'd pull the distributor cap off and look for moisture inside. Use compressed air to blow the distributor and cap out, rags and then a hair dryer to dry them out thoroughly. Avoid spraying them with WD40- it'll displace the moisture, sure, but the greasiness will attract dirt and cause more trouble in future.

You may also have water around the spark plugs- pull the leads off and give them a blast with compressed air too.

General procedure after ingesting water is to check the oil filler cap for milky "mayonnaise" after the engine's run a while- if the oil is creamy it's water, and you need to drain the oil, flush it with fresh oil, drain it again, and change the filter.

[LeighMc]

I'd pull the distributor cap off and look for moisture inside.

In the photo I attached of the engine, whereabouts is the distributor cap? Sorry I'm completely new to Delica engines.

[Growlerbearnz]

It's at the front- it's the thing that all 4 (5) spark plug leads plug into. Inside is a tab that spins around, directing the high voltage spark to whichever lead needs it- if it's got water inside, the moisture will be conducting the spark to ... well, anywhere really.

[LeighMc]

It's at the front- it's the thing that all 4 (5) spark plug leads plug into.

Thanks for that. I tried getting at it but the screws are pretty difficult to access. Don't have a decent set of screwdrivers at the moment so I'll have to source those nearby.

Also, what difference would the air intake being wet have? Would that cause the engine to slowly lose power and drop RPMs also?

The vehicle has also been super sluggish to accelerate or climb hills. Thinking back this actually started before the river crossings. I got the oil changed right before I did the river crossing trip as well.

[Growlerbearnz]

First thing: you never want water to get into the engine, either in the intake or in the oil. Water doesn't lubricate, and your engine will tear itself to pieces pretty quickly if there's water in it. It'll also rust, and the rust will act as an abrasive. Not good.

Water in the intake might have melted the paper air filter, which might be clogging things up? But generally a lack of power will be the water messing with your spark.

Though if the symptoms started after the oil change it might have been something they did while changing the oil. Petrol engines aren't really my forte. Well, modern ones (meaning anything newer than 1970).

[sk66]

I can only come up with two things based on the symptoms...
One would be some kind of sensor/adjustment that is supposed to change the air/fuel ratio as the engine warms up... maybe an automatic choke that's not working (opening)?
The other would be water in the fuel/filter... like it separates/drains back while sitting but after running a bit it gets mixed in to where it's too much.

Normally water/electrical issues cure themselves as it dries out over time. I can "kind of" see water in the distributor pooling in the bottom when sitting/cooled to where it doesn't interfere with the contacts. And then getting slung about/distributed by heat and rotation as the engine runs, but I've never seen/heard of it TBH. Sometimes water can get into an area easier than it can get out through evaporation...

It sounds to me like you're well beyond any of the potential major issues like water in the cylinders... but I would still check all of the oils for contamination.

Mine is also a diesel so I don't know anything specific about these gas engines in particular...