Cummins M2 300HP 6BTA 5.9

[superheat6k]

Latestarter my Cummins are Thornycroft marinised 6BT5.9M 210HP, so don't have CACs. The boat was built Winter 90-91, so likely has 1990 engines.

1 Anything I should consider paying specific attention to ?

2 Is it possible to upgrade them to 6BT'A' standard and gain some extra HP ?

3 I have noticed my Stbd engine cools down significantly on the 3 mile river jaunt back to the mooring, so I intend to replace the thermostats on both this Winter. Is the 86oC item ASAP sell suitable or should I go to Cummins for these ?

Thanks.

 

[Latestarter1]

Dear Sir
I am wondering if you could help me answering a similar question as Norri? I have a Jeantot 42 power cat with two 300 HP cummins 6bta 5.9 1995. I am not able to see the engine serial number and I wonder if you could direct me to where to look for.
Thank you so much

1995 6BTA 300 was completely different CPL from OP's motors which were CPL 950, differences too long to list,

however the new turbocharger which came with later CPL had far lower EGT at rated speed and passed off on U.S Navy 500 hour endurance torture test and was commercially rated as a result. This CPL was only superseded by switch to larger Bosch P7100 fuel pump with RQV governor allowing for release of the 370B.

Solid engine rest easy..

 

[Latestarter1]

Latestarter my Cummins are Thornycroft marinised 6BT5.9M 210HP, so don't have CACs. The boat was built Winter 90-91, so likely has 1990 engines.

1 Anything I should consider paying specific attention to ?

2 Is it possible to upgrade them to 6BT'A' standard and gain some extra HP ?

3 I have noticed my Stbd engine cools down significantly on the 3 mile river jaunt back to the mooring, so I intend to replace the thermostats on both this Winter. Is the 86oC item ASAP sell suitable or should I go to Cummins for these ?

Thanks.

Sorry Trevor missed your note.

#3 Is calorifier off the starboard engine?? Nothing wrong with replacing thermostats, however I would NEVER go hotter, a blockage on your raw water side or any other cooling system issue will cause temperatures to rocket in a trice, I tend to go for the QSB 6.7 71 Degree C stat in a B for greater cooling margin not less.

Cummins parts pricing has gone potty lately, aftermarket is fine.

#1 Your turbo feed will be off the rear of the head, experience showed that flow was marginal due to the flow restrictors in the head gasket, later engines picked up flow from rear of the block which offered far greater Delta T and therefore margin for when sh1t happens and dramatically lowers risk of manifold cracking.
One of the design differences when I was at Ford was the internal water flow arrangement compared with the Ford Dorset which always got mad 'ot' around #6 particularly on Sabre high output marinisations. On B Series Phil Jones team identified cooling this as potential issue and back of block has loads of cooling.

#2 The 250B similar vintage to your own engines caused huge embarrassment, Princess loved it and ordered significant numbers, this was no spec sheet 250, it really delivered the goods, however following rotor head failures of the DPA fuel pump in service lucas concluded that the higher output created a hydraulic shock when injector closed which shattered the rotor head and no technical solution was offered which caused a big falling out between Cummins, Lucas and Princess.

In the short term Cummins replaced the 250B's with de-rated 300B's with Denso inline pump in order to placate Princess customers, however cost Cummins big $$ and selling 300B's at 250 pricing was also untenable. Darlington engineering did eventually work out a robust fix to placate existing customers however the CPL was discontinued and no new engine ratings were ever developed with Lucas as a dancing partner again.

I do have the Darlington fix calibration on file however I have never had a B 210 CPL 742 pump apart and compared with the DPA 250 pump incorporating the engineering fix, never enough time!

 

[Latestarter1]

Trevor,

Not seen it myself however there is a 'watch out' for engine with low operating temperature issue.

Apparently the soft seat design of thermostat can be subject to the rubber becoming de-bonded which prevents the stat fully and also prevents it closing so certainly worth taking a look.

 

[superheat6k]

Trevor,

Not seen it myself however there is a 'watch out' for engine with low operating temperature issue.

Apparently the soft seat design of thermostat can be subject to the rubber becoming de-bonded which prevents the stat fully and also prevents it closing so certainly worth taking a look.

Thanks. If I observe any issues when I strip the alternator off and drain the coolant I will come back here.

Do the Cummins stats have a bypass close valve, or just a plain stat. ASAP do not state their standard 82oC (not 86oC) is suitable for Cummins, but it is a cheap as chips, so might order two anyway, and I have to order some exhaust hose and repair joiners anyway, but thats another story !

 

[Latestarter1]

Thanks. If I observe any issues when I strip the alternator off and drain the coolant I will come back here.

Do the Cummins stats have a bypass close valve, or just a plain stat. ASAP do not state their standard 82oC (not 86oC) is suitable for Cummins, but it is a cheap as chips, so might order two anyway, and I have to order some exhaust hose and repair joiners anyway, but thats another story !

Trevor whilst ASAP stat is certainly cheap the ones I searched appeared to be for Leyland applications and from the pictures had no 'jiggle pin' vent arrangement, in addition suitable thermostats have locating pin to ensure correct orientation. Finally Cummins stats come as a kit with a new rubber sealing ring, housing has no gasket it is a mechanical seal. The sealing ring must be replaced together with the thermostat as they go hard and leak if you try to reuse them.

PM me if you want some B thermostat kits.

 

[Princess 368 man]

Norrie,

I got your private message.

You posted ESN#s
11573018
44573855

The 11 # is clearly incorrect CPL 970's were build in UK Darlington serial 8 #s starting 21XXXXXX and US Rocky Mount 8 #'s starting 44XXXXXX.

44573855 came up stright away on the database:
6BTA 5.9M(300)
CPL 970
Built Rocky Mount 28th Jan 1991

Assumed that first serial was a typo and substituted 44 fot 11 however came up as not on the database??.

Some good news and some not so good.

#1 You have later Denso fuel pump with boost control. Early 6BTA 300's to

Hi , sorry to jump on this but I too have a pair of Cummins 6bta and I would like some info on the motors , ideally the internals and what what HP the motors could be rated to safely.
My esn's below

21085552
CPL 970
Cust spec SO 3133

21082987
CPL 970
Cust spec SO 3133

Any help and advice would be much appreciated.
Regards,
Pierre

 

[superheat6k]

The 6BT5.9M I have are rated for 210 HP.

I expect the 6BTA (after cooled) will have a considerable uplift, so suggest you see what Cummins website says. Burguundyben can likely provide a more comprehensive answer.

 

[burgundyben]

CPL is controlled parts list. You'd have to look carefully at the detail of 970 and compare to the other CPL's to know what could be achieved.

A quick google suggests CPL970 is 300hp, you'd have to look carefully at RWP, injection pump, turbo and charge cooler at a minimum.

 

[Princess 368 man]

Ah thanks how do I find out what the CPL 970 consisted of please and is there any order to CPL numbers?
Thanks,
Pierre

 

[AndieMac]

Latestarter my Cummins are Thornycroft marinised 6BT5.9M 210HP, so don't have CACs. The boat was built Winter 90-91, so likely has 1990 engines.

1 Anything I should consider paying specific attention to ?

2 Is it possible to upgrade them to 6BT'A' standard and gain some extra HP ?

3 I have noticed my Stbd engine cools down significantly on the 3 mile river jaunt back to the mooring, so I intend to replace the thermostats on both this Winter. Is the 86oC item ASAP sell suitable or should I go to Cummins for these ?

Thanks.

Hi superheat,
Latestarter asked if your calorifier was on the engine that was running cooler, just out of interest, was it? Did you find the source of the issue?
cheers

 

[burgundyben]

Ah thanks how do I find out what the CPL 970 consisted of please and is there any order to CPL numbers?
Thanks,
Pierre

Set yourself up with an account on Cummins quickserve and put your ESN in.

You might find a summary of the 6bt CPL's elsewhere online, have a look at SBMAR website.

 

[PCUK]

Anyone want a brand new Sherwood raw water pump for 6BTA M2?
£400.

 

[burgundyben]

Anyone want a brand new Sherwood raw water pump for 6BTA M2?
£400.

Funnily enough, I bought one on ebay last week, I remembered someone on YBW had one but I couldn't remember who it was, I wondered if I was unknowingly buying yours, I bought a Sherwood P1730, with the hose elbows, brand new, £220 delivered. They seem to be about £750 new.

I couldn't recall which one yours was.

I bought a couple of things from Latestarter too, I now have a complete kit to marinise a bus engine, its a slow time plan in the background.

 

[superheat6k]

Hi superheat,
Latestarter asked if your calorifier was on the engine that was running cooler, just out of interest, was it? Did you find the source of the issue?
cheers

Since I replaced the thermostats and flushed the fresh side of the engines the temperatures have been far more even - they now hover ~ 85 - 90oC nice and steady. Now about the bloody fuel system on the stbd ... !

 

[AndieMac]

Since I replaced the thermostats and flushed the fresh side of the engines the temperatures have been far more even - they now hover ~ 85 - 90oC nice and steady. Now about the bloody fuel system on the stbd ... !

Thanks for the reply, just trying to work out if the calorifier is a potential problem, a local boat with the same engines had a piston grab, mechanic blamed the calorifier for "cooling" the engine and removed it from the system. I hadn't heard of this happening before, so curious to find out.

 

[tbiker]

Dear Latestarter1,

Can you comments on my Cummins 6bta 5.9 m2 motor build, s/n 44612584? I am in the middle of purchasing an 1992 Ocean Alexander 440 with twin engines. These twins were rebuilt back in 2018.

Terry

 

[harvey38]

Hi tbiker,

Welcome to the forum.

Unfortunately this post was last updated over three years ago and Latestarter not posted since 2018.

It may be worth starting a new thread in the mobo section.

Let's see some pics of your potential purchase

 

[PCUK]

I've got a brand new Sherwood pump for this engine if you buy the boat and want to carry a spare.

 

[Bouba]

Dear Latestarter1,

Can you comments on my Cummins 6bta 5.9 m2 motor build, s/n 44612584? I am in the middle of purchasing an 1992 Ocean Alexander 440 with twin engines. These twins were rebuilt back in 2018.

Terry

While I cannot comment on your particular engines or the rebuild....these are legendary engines. And this is your holy grail Forums Archive