One for the resident diesel engine gurus...

[MapisM]

...with many thanks in advance for throwing some light on this.

I came across some Caterpillar documentation, specifically related to 3116 and 3126 engines, where it's stated the following:

Multigrade oils use high molecular weight polymers as viscosity index improvers.
When the crankcase blowby flows through the turbocharger and the aftercooler, the viscosity index improvers can adhere to the turbocharger compressor and aftercooler core.

Now, aside from the fact that I don't understand why this problem should only affect these two engines, the same paper goes on with another statement that made me curious:

Cat recommends the use of single grade oils that pass all API CF-4 category requirements unless crankcase blowby has been routed away from the air cleaner inlet.

This seems to imply that there could be an alternative installation for the crankcase blowby. Does anyone have an idea of what that could be?

 

[vas]

Cat recommends the use of single grade oils that pass all API CF-4 category requirements unless crankcase blowby has been routed away from the air cleaner inlet.

This seems to imply that there could be an alternative installation for the crankcase blowby. Does anyone have an idea of what that could be?

I wont dare deal with the first Q, I'll leave it to LS, tinkicker et al, but the above probably means that you can do what we sometimes do in cars, route the blowby with a long pipe down under the g/b
Maybe the equivalent is to run a pipe to the exhaust outlet at the transom? I have external grp chambers for the exhaust, I'm sure someone could easily dump the fumes there? Not me though...

cheers

V.

 

[david_bagshaw]

sabre use to vent crank case gases via a loop to a skin fitting.

very common till 80s to vent into the engine room.

 

[omega2]

sabre use to vent crank case gases via a loop to a skin fitting.

very common till 80s to vent into the engine room.

We still do but have improved it a bit, i.e we catch the muck in 2 litre plastic bottle, vented at the top to stop it exploding. LOL

 

[rafiki_]

First question MM, is why would you want to change anything if it is working well at the moment? Tinkering with engines seldom improves them. I was also perplexed to find that I could only use single grade SAE 30, but this is what Cat, Finnings and LS recommend. So who are we to disagree?

 

[MapisM]

First question MM, is why would you want to change anything if it is working well at the moment? Tinkering with engines seldom improves them. I was also perplexed to find that I could only use single grade SAE 30, but this is what Cat, Finnings and LS recommend. So who are we to disagree?

Well, actually several folks (and I'm talking of Cat professionals, not just fellow boaters) down here tell me that the Mobil Delvac 15W-40 is their preferred choice for most engines, 3116/26 included - hence my curiosity.
In fact, that's the stuff I threw into my engines at the last oil change, and I never experienced the higher soot that according to Cat should go with multigrades...
Btw, do you use the Cat branded oil (called "Special Application Engine Oil", or SAEO) in your engines, or anything else? And if the latter, what?

Oh, and for those who mentioned other, more or less "straight", venting systems: blimey, doesn't the stuff reach temperatures well in excess of 100°...?!? :ambivalence:

 

[rafiki_]

I use Exol Marine 123. This is rebrands as Cat in the UK, but does not carry the CAT (Cat Added Tax).

 

[sunquest]

I have TA3116's in my boat and used to buy my oil from Finnings which was Exol Taurus Sae 30 at around £90 for 25 ltrs. Later I found I could buy the same oil at half the price! Exol have now superseded their Sae30 oil with a product called Marine 123. Their distributor in Kent advised me this is the preferred oil used by the Port of London Authority in their craft. As is normal the price is around half that of Finnings at around £50 for 25 litres.

 

[Trundlebug]

I'm quite surprised that CAT route their crankcase ventilation back through the inlet (which is what I interpret from the OP's first quote).

My understanding was always that by doing so, there is a risk that if ever there's wear or other issue which could cause oil fume carry over, this could in turn lead to engine runaway.
Hence why (I thought) all boat diesel engines were vented to open air. I'd assumed closed circuit breathing systems were just a "No". Obviously not then.
I'll be interested to hear from the true experts in due course...

 

[rafiki_]

I'm quite surprised that CAT route their crankcase ventilation back through the inlet (which is what I interpret from the OP's first quote).

My understanding was always that by doing so, there is a risk that if ever there's wear or other issue which could cause oil fume carry over, this could in turn lead to engine runaway.
Hence why (I thought) all boat diesel engines were vented to open air. I'd assumed closed circuit breathing systems were just a "No". Obviously not then.
I'll be interested to hear from the true experts in due course...

This is one for Latestarter1

I expect that my Cats would need so much of this carry over that one would be well aware before it occurred, but I look forward to being corrected.

 

[Latestarter1]

...with many thanks in advance for throwing some light on this.

I came across some Caterpillar documentation, specifically related to 3116 and 3126 engines, where it's stated the following:

Multigrade oils use high molecular weight polymers as viscosity index improvers.
When the crankcase blowby flows through the turbocharger and the aftercooler, the viscosity index improvers can adhere to the turbocharger compressor and aftercooler core.

Now, aside from the fact that I don't understand why this problem should only affect these two engines, the same paper goes on with another statement that made me curious:

Cat recommends the use of single grade oils that pass all API CF-4 category requirements unless crankcase blowby has been routed away from the air cleaner inlet.

This seems to imply that there could be an alternative installation for the crankcase blowby. Does anyone have an idea of what that could be?

Mapis

It is all centered around the 31XX Series Cat motors and whether they are HUEI or MUEI. Obviously no HUEI on 3116.

Cat started seeing heavy residue deposits in the turbocharger and CAC with originally specified muligrade lubricants which was leading to rapid fall off in performance.

Cat originally addressed the problem (mainly due to the design of the closed crankcase breather design) with a CAT Special Application SAE 0 lubricant which caused ructions due to only being avilable from Cat dealers and high cost. Eventually they backed off by allowing a straight grade 30 or 40 weight lubricant to CF4.

However straight weight lubricants totally unsuited to being used as hydraulic medium in HUEI fuel system therefore closed crankcase breather system was re-designed and 3126 HUEI and successor C7 and 15W40 or 10W30 multigrade lubricants to CG4+.

No surprisingly users became confused as hell.

As to old style open crankcase ventilation I have a liking for use of 'puke' bottles as I hate the thought of returning oil carryover which contains products of combustion to the lubricant in closed crankcase breather systems but the Sabre arrangement of venting over the wall was pure stone age with oil streaks down the hull.

 

[MapisM]

As to old style open crankcase ventilation I have a liking for use of 'puke' bottles as I hate the thought of returning oil carryover which contains products of combustion to the lubricant in closed crankcase breather systems but the Sabre arrangement of venting over the wall was pure stone age with oil streaks down the hull.

Interesting. Do you see any reason why I couldn't detach the crankcase breather hoses from the air intakes, close the holes and put them in puke bottles?
I'd like to stick to multigrade in principle, but I don't fancy the risk of getting the turbo and aftercooler clogged...

 

[vas]

LS, informative post as always, thanks.
Am I guessing right that puke box is not an engineering term, but a homemade construction from a say 4lt plastic empty oil bottle or something like that?
And assuming the system collects any liquid/solid deposits, what happens with the rest of the "gasses" in the fumes? leave in e/r or divert out?

cheers

V.

 

[KevB]

My son fitted one of these to his car. Quite amazed by the amount of gunk it catches.

http://www.ebay.co.uk/itm/Oil-Catch-Can-15mm-Fittings-Universal-Breather-Tank-Crank-Case-Breather-Square/330674802885?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20141212152715%26meid%3D7cdede7ac34c45379458ed40f0671b72%26pid%3D100338%26rk%3D1%26rkt%3D23%26mehot%3Dpp%26sd%3D171546091774

 

[omega2]

They get sucked back through the engine, but what goes in does not foul your turbo too badly, and the intercooler can handle what does get in without clogging the reeds. All reburned and out through the exhaust pipe.

 

[tico]

nteresting comments. When I re-engined our previous boat and fitted Lancing Fords , they 'breathed' a bit heavy and I had to clean out the intercoolers on a regular basis as well as getting a gungy engine bay.

Cured by fitting (as i have discovered they are called) 'puke' bottles. Simple milk containers with open cell foam linings to filter out the oily residue. Worked a treat.... saved cleaning the CACs and kept the engine bay clean.

 

[vas]

They get sucked back through the engine, but what goes in does not foul your turbo too badly, and the intercooler can handle what does get in without clogging the reeds. All reburned and out through the exhaust pipe.

thanks,

so that means there is something more than a ally box there? A filter of some sort?

cheers

V.

PS. ok, tico explains how it works. May consider fitting something similar

 

[rafiki_]

LS is not a big fan of the 3126!

 

[Latestarter1]

Being a believer in keeping it simple and inexpensive here is arrangement I did for a Cummins B 260 from original thoughts by pal in U.S.

Let me explain principals.

Block off existing breather on engine side-plate. Use oil filler arrangement designed for a rear engine bus and fit to front gear cover. Top off filler tube with K&N air filter designed for industrial compressor.

Visited the pond department local garden centre and obtained selection of plastic fountain fittings including two 3/4 BSP to barb 90 degree elbows 3/4, 3/4, to 3/8 unequal Tee, some flexible tube and a chemical bottle.

The key piece is the small compressor filter drilled to take the the threaded elbow. We have diverted the blow-by from a high point on the engine leaving much of the oil vapour to condense on the front gear cover. The more volatile blow by rises up the tube induced by negative delta 'P' provided by the turbocharger until they meet the colder air being drawn in though the small air filter. The blow by gases condense in the downhill section of the flexible tube draining into the plastic 'puke' bottle, as the air is now being drawn uphill to the turbocharger air filter any remaining condensate falls back towards the bottle. The system can be regulated by unscrewing the jubilee clip on base of small air filter which adjusts the amount of suck from the turbocharger inlet, too much suck and we start see blow by entering the the turbocharger.

Essential parts from garden centre came to around £20.

My only comment regarding the Lancing system is that it it does not use gravity very well.

 

[Latestarter1]

Missed off attachments, please ignore comment re turbo water cooling inlet point.