Sleeved engines

[Tom]

This is a re-visit of the cavitation issue related to coolant. Previously I understood that this issue affected Cummins but not CAT engines because Cummins engines are sleeved and CAT engines are not. Last week I talked with a friend, an ex-CAT mechanic, who says he's rebuilt numerous CAT engines. He was quite emphatic that CAT engines are also sleeved.

His theory on why CAT engines might not suffer the same problem is that CAT goes to pains to channel the coolant in such a way that it's away from the direction of the sleeve.

Surely the answer can't be that simple and Cummins has either overlooked it or are locked out by some patent?

 

[Steve CDN]

I'll be looking forward to reading Leo's comments on this!!

 

[Jim Godward]

I don't know what Leo's answer will be but if you read the coolant requirements for the CAT 2136, you will find a similar requirement to the Cummins one.  Mine is checked every time it goes in for service and at 6 months if not serviced.  CAT coolant has the stuff in it too.

 

[Tom]

coolant requirements for the CAT 2136, you will find a similar requirement to the Cummins one.

Interesting Jim. I just looked at the manual for the 3196 CATs in the boat. It says that using ELC (extended Life Coolant), which I do, the frequent additions of SCA (Supplemental Coolant Additive) are not required. I knew there was a reason I hadn't added any SCA for the last 5 years  ;D

Reminds me, it's about time to change the ELC.

 

[John From Detroit]

Sleeved or not should not affect cavatation,  Coolant flow design (which cat says they take great pains when designiing) most deffently will, no question there.

So. I'd say the difference is CAT designed with elimination of the problem in mind,  Cummings needs to go to CAT design school

 

[blueblood]

This is a re-visit of the cavitation issue related to coolant. Previously I understood that this issue affected Cummins but not CAT engines because Cummins engines are sleeved and CAT engines are not. Last week I talked with a friend, an ex-CAT mechanic, who says he's rebuilt numerous CAT engines. He was quite emphatic that CAT engines are also sleeved.

His theory on why CAT engines might not suffer the same problem is that CAT goes to pains to channel the coolant in such a way that it's away from the direction of the sleeve.

Surely the answer can't be that simple and Cummins has either overlooked it or are locked out by some patent?

No, the answer is not as simple as directing coolant away from sleeve. The designs are fundamentally different. Cummins uses a so-called wet sleeve which allows for in frame overhaul. The larger bore in the block casting to accomodate sleeve creates areas in design that puts coolant against the sleeve and thus is subject to cavitation. The CAT has what is called a parent liner i.e. it is machined into block casting. In frame over haul can not be done and the usual method of repair is to use a re-manufactured engine. This design is not as prone to cavitation so it may be that CAT doesn't require additive but I'm not schooled on CAT so no real knowledge.

 

[Tom]

Thanks Leo. I'm not sure what you mean by:

.... a parent liner i.e. it is machined into block casting

Can't figure out if you're saying it's not a separate (moveable) liner. The guy I talked with said that the CAT liner/sleeve is separate from the block and, in fact, moves when the engine is cold, altough that's not desirable.

 

[blueblood]

Thanks Leo. I'm not sure what you mean by:

Can't figure out if you're saying it's not a separate (moveable) liner. The guy I talked with said that the CAT liner/sleeve is separate from the block and, in fact, moves when the engine is cold, altough that's not desirable.

The "sleeve" is bored directly in the block casting (parent).

I don't know the CAT lineup> maybe certain engines are sleeved. One would need to ask him what engine series he is talking about but in general CAT engines are parent bore in the sizes we are talking about.

The bore in block (parent)  is a cheaper alternative to sleeved. One is not necessarily better than other. Its a matter of determining the best cost alternative for the long term and weighing the probability of possible early failure and consequent repair cost of pulling an engine or doing being able to do an in frame overhaul in either case. 

 

[Tom]

Leo,

The way you just described it is how I previously thought you said it was. i.e. there is no sleeve/liner in a CAT engine.

I don't know the CAT lineup> maybe certain engines are sleeved. One would need to ask him what engine series he is talking about but in general CAT engines are parent bore in the sizes we are talking about.

I recall him saying he'd worked on farm equipment and large trucks. Can't recall if he mentioned anything else or if he mentioned an engine series.

 

[Chet18013]

I do not recall where I heard this, but all the CAT truck and large equipment engines are sleeved. The  non-sleeved engines were developed as a way to reduce costs for the RV manufacturers. --They are cheaper to build and very few RVs ever get enough miles put on them to need the total rebuilding that a sleeved engine can have.  Over the last 10 years, the RV engine use has grown to the point that they can demand a cheaper engine design --and get it. The cavitiiton problem is greatly minimized by the use of the correct coolant.

Chet181013

 

[Tom]

I tried nosing around the CAT web site and found a product support maintenance tip, written by CAT's Commercial Marine Manager, describing the cavitation issue. This suggests that CAT engines could suffer from a similar problem to Cummins engines, although it doesn't answer the sleeve issue per se.

 

[blueblood]

I tried nosing around the CAT web site and found a product support maintenance tip, written by CAT's Commercial Marine Manager, describing the cavitation issue. This suggests that CAT engines could suffer from a similar problem to Cummins engines, although it doesn't answer the sleeve issue per se.

I read that to clearly say he's talking about sleeved engines not parent bore.

 

[Tom]

I read that to clearly say he's talking about sleeved engines not parent bore.

You're right Leo. When I re-read it, this line jumped out at me:

Flexing of the cylinder wall (after fuel combustion) causes the cylinder liner to vibrate