Caterpillar engines

Hi everyone. Can anyone advice on known serviceability or problems associated with Caterpillar 3126B engines which reside in a Grand Banks Europa 46.
Cheers

The CAT 3126B is the older brother to the C-7 and has a very good service reputation.

The Caterpillar 3126 is a turbocharged 7.2L inline 6-cylinder diesel engine manufactured by Caterpillar and first introduced in 1997; it was the first electronic mid-range diesel engine that Caterpillar produced.[1] It is the successor to the Caterpillar 3116 engine and was replaced by the Caterpillar C7 engine in 2003.[1] It is a medium-duty engine and has been used in dump trucks, long haul trucks, ambulances, buses, RVs, boats, cranes, fire trucks, and more.[2] In 1998, Caterpillar released an improved version, the 3126B; in 2002, the 3126E was released; though these improved versions only affected engine electronics, not the actual engine design.[1] Caterpillar launched a three-tier system of overhaul kits for the 3126 and its C7 successor in 2011.[3]
It was rated for multiple power applications from 170HP to 330HP

Great. Thanks for the reply. Engines have 2000 hrs. At these hrs what are the expected maintenance requirements. Major overhaul??

Our prospective boat is a 2005 model with the 3126B so why would it still have the "B" instead of the "E" engines?

Can't answer the E vs B but any reasonably maintained Cat engine should be able to go 10,000 hrs before rebuild time easily.

CAT 3126B service video

Our CAT 3116’s have 4,900 hours. Never a minute of trouble and smooth as silk.

It takes awhile for engines to pass through the system. Engine is built in 2003 then it’s shipped to a distributor. Early 2004 builder calls for an engine. Boat is finished late 2004 but is given a 2005 designation because it takes time to sell and deliver a boat. Boat goes to a boat show Jan 2005, sells/delivers in July. By now the engine is two years old but zero hrs.

fgarriso said:

The Caterpillar 3126 is a turbocharged 7.2L inline 6-cylinder diesel engine manufactured by Caterpillar and first introduced in 1997; it was the first electronic mid-range diesel engine that Caterpillar produced.[1] It is the successor to the Caterpillar 3116 engine and was replaced by the Caterpillar C7 engine in 2003.[1] It is a medium-duty engine and has been used in dump trucks, long haul trucks, ambulances, buses, RVs, boats, cranes, fire trucks, and more.[2] In 1998, Caterpillar released an improved version, the 3126B; in 2002, the 3126E was released; though these improved versions only affected engine electronics, not the actual engine design.[1] Caterpillar launched a three-tier system of overhaul kits for the 3126 and its C7 successor in 2011.[3]
It was rated for multiple power applications from 170HP to 330HP

Click to expand...

We must of had a early release factory experimental 3126 in our 96 OA it was rated at 425hp and was aftercooled... I suspect your Wikipedia cut and paste was misinformed... While we never had had any serious issues with the 3126 it does require special Cat supplied oil at about $25 per gallon. Ours was not the B series and required special tools for the injection timing. Over all it's like most diesels each one has it's own strengths and weakness's

There is a Cat certified truck mechanic on YouTube, Adept Ape https://www.youtube.com/channel/UCxzsGzNaf85PAb0uXWTlWPw
He has a number of videos on Cats and a number on general diesel knowledge.

Great thanks

Thanks for the reply

There were a couple of updates over the years to the heat exhchangers/coolers, partly due to some failures with the original designs. Failures in these parts results in salt water mixing with engine oil and potentially an expensive rebuild. They are good engines but do your homework on the coolers. You need to know the type and condition of the coolers. My Cat guys recommend disassembly and service of the coolers every 3 years or so. Not an inexpensive job (find out how much, because you will need to do it), but cheaper than a failure.

We have C7s in our 2006 GB46, about 1850 hours.

Great engines in our experience, reliable and frugal and CAT has all spare parts readily available. I have been very happy.

Known ‘weak points’ on 3216B and C7 are aftercoolers and HEUI pumps.

CAT released upgraded/modified aftercoolers and cores in about 2011, they were a positive upgrade and if the boat you are looking at doesn’t yet have them installed you might consider allowing for that upgrade when deciding what price to offer. In Australia the cost was about AUD $12k per engine from CAT.

In relation to HEUI pumps, if the boat you are looking at has done 2000 hours then these pumps should be fine? In OZ it costs about AUD $4k from CAT if you need to replace one.

Good luck!

Hamish.

Thanks Hamish

Yes, the early 3126's had major aftercooler leaking sea water into the internals problems due to dissimilar metals expansion/contraction/corrosion issues. Many revisions have been done over the years to improve the sealing. Be sure you get a competent Cat rep to survey and make sure you have a newer revision, then keep up with diligent maintenance.

The 3116 uses engine coolant not sea water so did not have the same issues

The 3116TA, 3126TA, 3126B and C7 are all in sort of the same family, with lots of evolved differences.

I have been involved with many and my opinion has boiled down to this: If you work these engines HARD (like running 2500 on plane), they don't live long.

Run easy like 1600-1800, they can go dang near forever. So in a trawler where you run hull speed, they can do very well.

I think a good bit of the problems with charge air coolers is not so much leakage, but natural condensation poorly managed.

Thanks for the reply. Can you please explain the last paragraph relating to the problems with charge air coolers and the problems with natural condensation thats poorly managed? ?

Ski will be able to provide a better and more technical response, but in the interim my (non mechanical) understanding is this:

Situations of cool outside water temps meeting with the hot, compressed turbo charged air creates condensation in the air side of the aftercoolers. If that condensation water sits there for a long time, obviously it can corrode things and lead to bad problems.

One method of dealing with the phenomenon, as I think Ski has said somewhere else in another thread, is to run the engines at lower rpms for a while before shutdown (so the reduced charge air in effect dries out the condensation).

Another method is seen on the modified coolers on our CAT C7s - as with the coolers on the newer Cummins QSC8.3 - in that the coolers are sloped downwards on the underside towards a drain hole which has a sort of 'valve' (I am not a mechanic, so maybe I have described this wrong?) in it - the valve only opens when the engine stops and the air charge pressure backs off, allowing all the condensate to then drain from the cooler and not sit in there rusting or corroding. It is a good solution while it works, maybe not so good if the valve sticks (hence a good idea to check the valve from time to time).

Ski, did I get it right??

Hamish.

Cool, thanks for the explanation.

Hamish- Very good summary. When running at high boost (high power setting) and especially with cool sea water, there is lots of condensation occurring in the charge air cooler (aka aftercooler). This "mist" goes right into the air intake, but due to high temps in the cylinders it does no harm. If you shut the engine down soon after a hard run, the cooler core stays damp and drips and that moisture corrodes things, including the core and housing and intake valves. Many do have channels and drain valves to handle this, to varying degrees of success. You want to make sure the drain valves work. They open at low boost, and close as boost goes up, and can be prone to getting stuck.

But the best thing you can do is run the engine at very low load, say 1000rpm for like a half hour after a hard run and this will tend to dry out the cooler as there is basically no compression from the turbo, but still plenty of air flow. Most important if you know the boat is going to sit for many days or weeks after shutdown. Not so important if you are going to run again the next day.

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We have 3126B’s. Ours are rated to 450hp. You should be able to get the engine history downloaded over the Canbus by someone with the right computer. Look for a complete history with no missing bits. The aftercoolers should be serviced regularly along with all the raw water coolers. Don’t worry about a bit of underloading because frankly if you ran these things at 450hp all the time they wouldn’t last long. When you do the 200hrs service remove the air filter and check for oil in the turbo housing. If there isn’t any then they are going ok.

Brilliant information. Thank you.

The issues to investigate are:

1. Have the after coolers been replaced? Are they single pass (seawater input and output on opposite sides) or double pass (seawater input and output on the aft end)? The double pass was an important upgrade. Which ever you have, you will need to have spare o-ring seals for the input bonnet end to clear any debris or broken impeller blades. If you have the double pass upgrade, Catepillar will not be able to find any parts breakdowns. Here are some part numbers

Aftercooler
Double hose end 277-6198
Conversion kit 277-6201
Generic O-ring seal 152mm ID 3.53mm diameter #258

2. The orginal 3126b design had a hydraulic hose connecting the HUEI pump to the cylinder head. This hose has a tendency to fail at inopportune times. There is a steel tube conversion that should be installed. (beware, there are multiple versions of this tube that are specific to the after cooler or air input manifold. The version that fits with the marine after cooler is listed below).

High pressure HUEI line
228-7089 O ring seal
214-7568 O ring boss seal to HUEI pump elbow
6V-8724 90 degree elbow

247-3755 Tube pipe

6V-8636 upper connector
214-7568 O ring boss seal
221-3494 O ring seal

3. You need to be have a replacement spool valve 122-5053

spool valve seals
033-6028 tip
123-3132 mid
033-6039 next to coil

There are some YouTube videos about this part (search Caterpillar 3126b). It is easy to replace and is the usual suspect in port running or hard to start engines.

4. Use Rotella 10-40 oil.

This is brilliant advice. You're a wealth of knowledge. Thank you very much.

Hello. I can still advise this resource here.http://catselleronline.com/ Hope it will be helpful.