Cat 3406B

[Joe]

Two of my trucks have 3406B caterpillar's in them. Both 1992 Freightliner's. One surges at idle with the Rpms constantly jumping. Does anyone know how to correct this problem so i can get a normal smooth idle? On my other 92 sometimes i cant get more than 50MPH out of it and other times its completely normal. I can be driving at 60 and all of a sudden the engine will die down and hold at 50MPH. Any help would be appreciated thanks.

[chupis]

what pumb do have mecanical,semielectronic

[Joe]

Its semi electronic has a sensor where the throttle shaft would normally be. Both trucks are semielectronic

[DAS]

it sounds like a peec engine and they have to check the parts inside that housing where the wires come out, there more to it,than just opening it up, best to take it to a shop that has the right tools. also they will work with the advance unit, it all works together.

[farmerbart]

DAS wrote:

it sounds like a peec engine and they have to check the parts inside that housing where the wires come out, there more to it,than just opening it up, best to take it to a shop that has the right tools. also they will work with the advance unit, it all works together.

you can take mechanical pump and put on it.

[r smyre]

if it truely is a 3406b there are no electronics this is a mech pump elec would have nothing to do with this engine surging

[Roy Duenas]

We have a 1988 Kenworth with a 3406b Caterpillar engine. The radiator is building up pressure and coolant is blowing out when it is being driven. Can someone please tell me why this is happening? The engine was recently overhauled. Thanks!!

[DynPro]

Roy Duenas wrote:

We have a 1988 Kenworth with a 3406b Caterpillar engine. The radiator is building up pressure and coolant is blowing out when it is being driven. Can someone please tell me why this is happening? The engine was recently overhauled. Thanks!!

most likely you have a blown head gasket, but there are several other things that may cause this:

- Missing Fuel nozzle adapter seals. for some reason these steel ring type seals are missing from certain gasket/overhaul kits. this might be the case if you just had an overhaul. also if the rings are missing your engine will suffer from poor combustion and white smoke due to unburned fuel, this because once the rings are missing the fuel nozzle & adapter sit 2,5 mm deeper inside the combustion chamber.

- A cracked fuel nozzle adapter sleeve. the sleeve is surrounded by coolant and if the tip thread (which reaches the combustion chamber) has cracked it will definately leak combustion pressure into the cooling jacket. during sleeve installation one must make sure to use proper tooling, in some cases a too small or worn tool has caused the sleeve to crack from the valvetrain side during installation, thus leading to a coolant leak to the oil compartment.

- A failed cylinder liner. the liner flange or wall may have cracked. there also may be heavy corrosion spots on the liner coolant surfaces, which when severe enough usually leak only one way, combustion pressure into the cooling jacket.

- Corroded cylinder block top deck surface. if the contact surfaces for the cylinder liner flanges are corroded the liner projection (alignment) will fail and reduce the compression on the flame ring on the head gasket.

- A crack in the cylinder head.

hope this helps, cheers

[chupis]

Roy Duenas wrote:

We have a 1988 Kenworth with a 3406b Caterpillar engine. The radiator is building up pressure and coolant is blowing out when it is being driven. Can someone please tell me why this is happening? The engine was recently overhauled. Thanks!!

check if sleeper has a small valve that works with air to open the heater, sometimes the valve fail and the air passes to the water

[Eron]

I have a 1994 3406 cat and i just was checking the radiator fluid and found diesel fuel floating on top of the coolant resivoir. upon draining the coolant, I found that it was almost a gallon of fuel. I have heard different diagnosis from different people, what say you???

[DynPro]

Eron wrote:

I have a 1994 3406 cat and i just was checking the radiator fluid and found diesel fuel floating on top of the coolant resivoir. upon draining the coolant, I found that it was almost a gallon of fuel. I have heard different diagnosis from different people, what say you???

if your engine is a mechanical 3406 the only option is a failed fuel cooler (if equiped).
a blown head gasket may cause fuel to build up but it would also generate overheating, overpressure and soot in the cooling system.

if your engine is electronically controlled (MEUI), one of the fuel injector adapter sleeves may have cracked. it could also be the optional fuel cooler.

please let us know the results if your engine happens to be a mechanicallý controlled one.
hope this helps, cheers

[Eron]

It is an electronic motor. The mechanic that i spoke to over the phone was very confident that it is the injector cups(sleeve) that are cracked, like you said. It offers me more comfort that my mechanic wont find anything else wrong when i get more info from people like you. Thanks.

[DynPro]

Eron wrote:

It is an electronic motor. The mechanic that i spoke to over the phone was very confident that it is the injector cups(sleeve) that are cracked, like you said. It offers me more comfort that my mechanic wont find anything else wrong when i get more info from people like you. Thanks.

either its a crack or a corrosion spot in the sleeve or the sleeve upper seals have failed. theres virtually no other way for fuel to get in contact with coolant.
it would be wise to change the whole set of sleeves and seals.

also remember that theres a high risk that the fuel in the cooling system has already damaged your cylinder liner seals and other rubber based seals in the cooling system (temp regulator end seal etc). after repairing the fuel leak and properly flushing the cooling system you should keep a close eye on engine temperature and your oil level. take regular samples of both oil and coolant and send them to a cat dealer for analysis.

cheers!

[Eron]

The cat mechanic has looked into it today and says it is the injector cups. When you said "sleeve upper seal" you mean the part that seals the injector from the cooling system. And yes we are changing all the rubber seals that we can get to. Thank you, i will watch the temp and oil and make sure everything looks brilliant.

[shtc]

sounds like a blown head gasket. i had a john deere engine doing the same thing recently. head gasket was cracked.

[jamesrg]

what is the best way to replace the cam gear a a CAT 3406B mech. and still keep the timing

[Frank T]

Joe wrote:

Two of my trucks have 3406B caterpillar's in them. Both 1992 Freightliner's. One surges at idle with the Rpms constantly jumping. Does anyone know how to correct this problem so i can get a normal smooth idle? On my other 92 sometimes i cant get more than 50MPH out of it and other times its completely normal. I can be driving at 60 and all of a sudden the engine will die down and hold at 50MPH. Any help would be appreciated thanks.

Joe check your transfer pump , there are some small ckeck valves rubber in nature , they sell a kit to overhaul that pump rather cheap , and its a very easy job

[Frank T]

Eron wrote:

I have a 1994 3406 cat and i just was checking the radiator fluid and found diesel fuel floating on top of the coolant resivoir. upon draining the coolant, I found that it was almost a gallon of fuel. I have heard different diagnosis from different people, what say you???

Just off the top of my head I would say you have injector cups leaking , hopefully no anti- freeze got into your fuel tank

[chupis]

i think that he has a warming fuel that it will turn to rust and the diesel passes water. you need to elimenate that, easy to fix

[Drinkingdeath01]

Hi guys,I could use some help with my engine.I have a 89 Freightliner with a 3406b model Cat and I have water/coolant in the engine oil.I know this is bad but I'm hoping its a easy fix.The history on the engine is that its been overhauled in the last 70k by the previous owner.I have the paperwork from Cat on this.The problem is that I bought the truck and due to my service in the military it sat unstarted for the last year and a half.Before I left I had to replace the air compressor and when I came home and started it I noticed the oil was contaminated.I can't imagine the head gasket leaking already but I don't know.A friend of mine thinks it might be the seals around the cylinder rings.I hope this is not the case but again,I don't know.The Freightliner service manual says that internal leakage can be anything from a cracked head,head gasket,oil cooler,air compressor to bad rings.I really could use some help with where to start looking.Any hints would be greatly appreciated.Thanks much!!!!!!