Cat Diesel Engines

Jezz I feel like I'm driving on borrowed time, another thing to worry about

Mine has a 3126 B with 40,000 miles and not a single issue. Oil and filter changes yearly, valve lash adjustment done at 32,000 miles. Keep an eye on the belts and it runs,runs,runs!

Swamp Man wrote:
Been looking at the used MDT market and see a ton of trucks with CAT 3126, C-7, etc engines for sale. During my research it seems these engines allegedly have a lot of problems. I say allegedly as with any research on the net, you have to be careful. Any have one of these engines and how does/did it work out for you? I am aware that there are engines with failures that occur due to manufacturing defects in every brand. Some of the trucks listed have a good price but the old saying about if it sounds too good to be truth, it is.

All right, now that all the fan boys of the Cat can do no wrong have checked in, lets talk about some of the common problems with the C-7. :B

Before all the fan boys get all froggy on me let me first say that Cat makes some damn fine engines. Most of their stuff is anvil reliable and built like a brick,,,,,,,well you know. Unfortunately the C-7 isn't one of them.

Problem #1 is the HEUI. Back in time this was thought by Cat to be a good system. Years later Cat saw the error of their ways and dropped the whole oil pressure injector deal like a hot potato much like International did.

Problem #2 is injector cup leaks. My friend worked on diesels for over 35 yeas said they were a nightmare. He said the early ones with the copper cups were a bad deal. He said they came out with stainless steel later and that helped things a lot.

Problem #3 is the HEUI and injectors are very expensive and like I said above, have a bad habit of going out.

Problem #4 is when the HEUI goes out it is much like the CP4 pump. The HEUI have a bad habit of taking a dump and when they do it takes the WHOLE fuel system out with metal everywhere. Can you say, BIG BUCKS!

Here is a little reading about the C-7 common problems.

If you want the real story about the C-7 go to a Cat dealer and talk to a gray hair tech about common problems with this engine. Most will give you the true story.............both the good and the bad.

The 3126 is one of the few Cat's that does NOT have replaceable sleeves. Comparing it to a C15 or even 3406 is night and day. A 3126 is a great engine for a MH that will never see 200K miles BUT this post was about MDT trucks converted to tow vehicle service. I would stay away from a high mileage truck with a 3126/C7.

I have owned a lot of Cat engines over the years and if they put one in a pickup I wouldn't even look at anything else. I have never owned a C-7 but Cat has the best shops and dealer network in the US. Take it to Cat and have them hook it up to their computer and check it out. I have some C-15 Cats that ran a million miles, where rebuilt by Cat in 3 days and are now almost at 2 million miles with very,very little ever going bad on them. If it's a Caterpillar engine I like it. Tried and true if you maintain them right !!

The 3126 is only a OK engine when you start pumping out 300HP. Way to many adds with rebuilt engines when you get above 400K miles. The Cummins 8.3 seems to be good for 600K and yes I,ve spent a lot of time and money on this subject. I,d rate MB best, 8.3 next, 3126 next, and Cummins 5.9 last BUT because of it,s smaller size, not reliability for towing larger trailers.

My Cat has run for 10 years with no problems. 78k miles now.
Both Cat and Cummins are solid engines. They all have probs once in a while.
My Cummins friends have had their share.

we have a 1999 Freightliner FL-60 four door, when I was looking I talked to my buddy that drives tow truck and the company had International and Freightliner he has a lot of time in both trucks, and he said Freightliner hands down for power, handling, the ride, well we listened and found ours on ebay for $30k, I towed my 42 foot fifth wheel toy hauler with my 1990 dodge diesel SRW and with my Freightliner, that triple air ride system of the Freightliner makes a 500 mile trip seem a walk in the park, now as far as the CAT motor, we got lucky and ours had been rebuilt by CAT and had 2K miles on it when we got it, our trailer is 16,000 and the truck with full tanks and tools is 13,000 so without a doubt we are NOT the first people to the top of the hill, but we are the most comfortable going up and coming down, have you thought about stepping up your game and going with a full semi built for towing RV's ? heres a picture of our truck and trailer >>> http://www.pinterest.com/pin/551339179353517264/

CAT C7 are great engines. All engine manufacturers have the occasional bad run of a component. I have been very happy with mine.