Oil/Water Light DT466

[JayLikesBus]

I have an early 2000’s I believe 2002 Amtrak International with a DT466 diesel engine.

I moved my coolant lines out of the bus and rerouted them under to the heater in the front. When I went to drive the bus about 3 miles down the road the oil/water light came on, but it goes on and off. Like as I’m driving it’ll be on for a minute and turn off for like 20 seconds. Strange.

The bus temperature gauge shows normal temp and the oil pressure gauge is at 50 psi still and looks fine.

Maybe I have to add more coolant to the lines I drained? I added about 2 gallons of the Final Charge 50/50 already. What’s the process if I do need to add more coolant? Thanks for any help I really need it!

[dbsoundman]

Oil in coolant would indicate the cylinders are leaking I believe. I would check your coolant level and test the coolant (I believe it’s referred to as an SCA test?) to see what the coolant condition is. Get a black stone labs test kit for your engine oil too.

[JayLikesBus]

I thought the oil/water light on the DT466 either meant low oil/coolant or overheating? Is that wrong?

[JayLikesBus]

I should still test it thought so I would like to find those testers for sure. Does anyone have any recommendations on where to find a good test strip set?

[dbsoundman]

Here’s some discussion that might help:
https://www.thedieselgarage.com/thre...-lights.87872/

Oil/water is a serious issue so you’ll want to trace this out sooner rather than later. There is a decent chance it’s a sensor or gauge cluster issue but I wouldn’t ignore it for too long.

[JayLikesBus]

Yes I agree. Definitely of concern. If I can’t figure it out I’ll take it somewhere. Although I’m 99% sure it’s something I did with the coolant.

[ewo1]

Pull your dip stick ASAP. Check the color of the oil, if it is clear then it is clean, black color - normal, grayish ---BAD, milkshake oil!

It is a really good idea to check your dipstick quite frequently!

[JayLikesBus]

I’ll check it tonight and see what it looks like

[mmoore6856]

i have never seen or heard of a lite that indicates water in the oil or vice versa. your sending him down the wrong roads.

[JayLikesBus]

Yea I figured that out after some research. The light definitely indicates either low coolant or low oil. I have a specific light dedicated to and says on the dash “ water in oil” and that’s not the light that’s illuminated.

On the other hand, I went down and checked my oil and it looks fine, no signs of water/coolant at all.

And I went ahead and ran the bus for 20 minutes idle with the radiator cap off and refilled with coolant when I was done and no more light. We will see what happens when I drive it tomorrow. Maybe some air got stuck in the system? I still haven’t got my defrost to work though :/

[cadillackid]

the oil / water light is triggered by an over-temp or by low engine oil pressure.. on the mechanical and gen-1 (3 box) DT466E the temperature portion used a separate sensor on the head for the temp..



on the single box 466E I believe it uses the ECM data.. Id have to look in the book for the 466E but on my 444E the light triggers if the oil PSI is below 8 for longer than 5 seconds at a time.. or if the engine water temp reaches 235..



there may still be a separate sensor that can trigger it as well.. its entirely possible you have air going through the coolant lines.. this will do a couple things..



1. one part of the engine can get really hot while another may remain normal.. a separate sender would trigger the alarm while the dash gauge reads normal..


2. air in coolant lines can cause the dash gauge to lie..



I would definitely make sure you are circulating coolant (if your valves are open your heaters should be HOT) when the engine is warmed up... if the heaters are off the engine warms up the radiator fan should move warm air and both upper and lower radiator hoses warm (in warm weather)..


if you dont troubleshoot that light the result may very well be water in the oil.. measning a single major ovewrheat event on a DT466 can destroy the liner seals and result in coolant in the oil pan and necessitate and in-frame..



it could be a faulty sensor or a computer wit han attitude but the baseline is verify that you are circulating and that the cooling system is working right and air is purged ..



these engines dont generally run hot on a normal basis.. my DTA360 rarely ever goes above 195 ..

[JayLikesBus]

Yea I ran it for about 30 minutes idle last night and never went above 180°. When I first turned the bus on I had the oil/water light so I went and added more coolant and ran it with the reservoir cap off and the light went out.

Both coolant hoses in the engine feel hot, however when I open my heater valves only one of them seems to get hot and the return one doesn’t and my heater doesn’t get hot. So either there’s air trapped in the line or I mixed up the hoses or something. This is the only issue I seem to be facing now. I monitored my oil pressure and checked it and it all seemed fine ��*♂️

[JayLikesBus]

I might take my two coolant lines to the front heater and loop them and see if that loop gets hot. Good idea or bad?

[cadillackid]

OK so is this a front engine bus? a rear engine? I understand you ran the heater lines under the bus for the rear heater? did you delete any heaters?


make sure there isnt a secondary valve on your driver console.. my Bluebird has 2 valves under the hood and then has a valve on the driver unit itself..


some busses have a hot / cold knob similar to a car and that has to be set to Hot for coolant to circulate through the heating system..

[JayLikesBus]

Oh for sure I’ll definitely check for that second valve tonight. Was it under the drivers feet or near the heater?

And it’s a rear engine bus

[cadillackid]

rear engine bus.. it may be that the water pump at idle just doesnt have the guts to push the water all the way through all the heater cores.. turn on the booster pump and that should help with that.. my bluebird valve is right on the heater console itself..


one of my friends has a thomas HDX and it has a heater control like a car with hot / cold and you have to have the levewr on full hot for the front valve to open..



ive seen some IC RE busses have a series of levers on the dash and you have to have the one for "heat" full on.. other levers in that panel control defrost or driver directionals..

[JayLikesBus]

Yea my console has the same controls. Under the dash there’s a lever that’s known to be stuck that I found last night and that might be the issue. I’ll try and mess with it tonight after I kill the hornets lol.

I’m going to take it for a small ride tonight and see if I can find anything. Maybe driving it like u said will get the heater going. Thanks man for the help I really appreciate it. These busses are a whole another level when it comes to mechanical!