3126 soft blocks

Homewrecker1

New Member
Jan 9, 2018
9
Pickwick Lake, TN
Boat Info
302 Baja 2003 refurbished (sold)
2004 342 Rinker (sold)
1998 450 Sundancer
Engines
Diesels 3126s
Looking at a 450 sea ray to buy . Has the 3126 cats, will serial number tell if they are the "soft" blocks ? Or how are they identified ?
 
Looking at a 450 sea ray to buy . Has the 3126 cats, will serial number tell if they are the "soft" blocks ? Or how are they identified ?

blow-by test during the CAT survey is the only true way to know. How many hours on the engines? If it’s more than a few hundred you’re very unlikely to have either the soft block or valve issues, they would have surfaced a long time ago if ran regularly

Blocks with FAPS stamped on them could be, but not all faps engines are soft. CAT does not have a way of telling you by SN.

if you search you’ll find many, many, threads. Most of which @fwebster has chimed in and set us straight which I suspect he’ll do here as well :)
 
I have nothing to add to Ryan's post.

Except, He is correct. The only true way to tell if a 3126 has soft blocks is to check the blow by to see if the cylinders have prematurely worn to the point where the blow by is at a level that isn't reasonable for the hours on the engines. On soft block engines, you will see high blow by on, sometimes with just a few hundred hours on the engines.

Two final points are: 1.)Caterpillar has very good technical data on their engines. They have a proprietary "blow -by gauge" that is a very sensitive pressure gauge that they connect to the crankcase vent system to measure the pressure of the combustion gases escaping past the piston rings into the crankcase. If you make an offer on this boat, you need to condition that offer on a mechanical survey, which should be done by a Caterpillar dealer who is equipped to do the blow by test and can pull oil samples on the main engines, the generator, the transmission fluid and the coolant on the Caterpillars and the generator.

2.) Caterpillar stopped warrantying the soft blocks in about 2004 so there is no recourse here other than rejecting the boat completely if you happen to find soft blocks. However, keep things in perspective here.....the chances of the 450 you are looking at being a soft block boat is pretty slim if she has normal hours. If, however, you decide to reject her for any reason, don't despair: this isn't the only 450DA on the market. Here is another one that doesn't have soft blocks, has at least 10 years of oil samples available for a buyer to review, has no deferred maintenance;/ is current on all maintenance and needs nothing. Please forgive the "self promotion", but this boat is mine and there are no secrets. If you can handle the location. I don't think you will find a nicer or better maintained 450:

https://www.boattrader.com/boat/1996-sea-ray-450-sundancer-7628533/
 
Get the serial numbers of both engines and call CAT... They told me about my 3126's being warrantied.
+ all of the above...
 
I have nothing to add to Ryan's post.

Except, He is correct. The only true way to tell if a 3126 has soft blocks is to check the blow by to see if the cylinders have prematurely worn to the point where the blow by is at a level that isn't reasonable for the hours on the engines. On soft block engines, you will see high blow by on, sometimes with just a few hundred hours on the engines.

Two final points are: 1.)Caterpillar has very good technical data on their engines. They have a proprietary "blow -by gauge" that is a very sensitive pressure gauge that they connect to the crankcase vent system to measure the pressure of the combustion gases escaping past the piston rings into the crankcase. If you make an offer on this boat, you need to condition that offer on a mechanical survey, which should be done by a Caterpillar dealer who is equipped to do the blow by test and can pull oil samples on the main engines, the generator, the transmission fluid and the coolant on the Caterpillars and the generator.

2.) Caterpillar stopped warrantying the soft blocks in about 2004 so there is no recourse here other than rejecting the boat completely if you happen to find soft blocks. However, keep things in perspective here.....the chances of the 450 you are looking at being a soft block boat is pretty slim if she has normal hours. If, however, you decide to reject her for any reason, don't despair: this isn't the only 450DA on the market. Here is another one that doesn't have soft blocks, has at least 10 years of oil samples available for a buyer to review, has no deferred maintenance;/ is current on all maintenance and needs nothing. Please forgive the "self promotion", but this boat is mine and there are no secrets. If you can handle the location. I don't think you will find a nicer or better maintained 450:

https://www.boattrader.com/boat/1996-sea-ray-450-sundancer-7628533/

Frank, something I'm not sure I asked when buying our boat that might help others reading this thread some day -

Are these two statements accurate?
  • Blocks stamped with FAPS might be soft, but not all were (blow-by is the only way to confirm)
  • Blocks not stamped FAPS were not soft
 
To answer your specific questions:

  • Blocks stamped with FAPS might be soft, but not all were TRUE(blow-by is the only way to confirm).THE BLOW-BY TEST WILL CONFIRM PREMATURE CYLINDER WEAR , BUT WILL NOT NECESSARILY CONFIRM THE PRESENCE OF A SOFT BLOCK
  • Blocks not stamped FAPS were not soft UNKNOWN.

The Service Manager at Ring Power in Florida, who is the Cat distributor that sold all the Caterpillar engines to Sea Ray told me that "only 3126 engines had soft blocks, hence, there were no 3116 soft block engines. HOWEVER, IF YOU OVER LOAD 3116's, YOU CAN CREATE PREMATURE CYLINDER WEAR GIVING YOU THE SAME OUTCOME; LOW COMPRESSION, LOW POWER AND LUBE OIL MIST ON AND AROUND THE ENGINE. The other fact was that the bare block as they left the foundry were not tested for hardness and some were soft while others were not. Therefore, a French cast FAPS block could be soft, could be either a 3126 or a 3116, but it remains to be seen how a company like Caterpillar, that put a 5 year warranty on a $75,000 engine would have a manufacturing procedure where their key component, the engine block, covered by a 5 year warranty could lose its identity and not be traceable after the initial machining was done.
 
To answer your specific questions:

  • Blocks stamped with FAPS might be soft, but not all were TRUE(blow-by is the only way to confirm).THE BLOW-BY TEST WILL CONFIRM PREMATURE CYLINDER WEAR , BUT WILL NOT NECESSARILY CONFIRM THE PRESENCE OF A SOFT BLOCK
  • Blocks not stamped FAPS were not soft UNKNOWN.

The Service Manager at Ring Power in Florida, who is the Cat distributor that sold all the Caterpillar engines to Sea Ray told me that "only 3126 engines had soft blocks, hence, there were no 3116 soft block engines. HOWEVER, IF YOU OVER LOAD 3116's, YOU CAN CREATE PREMATURE CYLINDER WEAR GIVING YOU THE SAME OUTCOME; LOW COMPRESSION, LOW POWER AND LUBE OIL MIST ON AND AROUND THE ENGINE. The other fact was that the bare block as they left the foundry were not tested for hardness and some were soft while others were not. Therefore, a French cast FAPS block could be soft, could be either a 3126 or a 3116, but it remains to be seen how a company like Caterpillar, that put a 5 year warranty on a $75,000 engine would have a manufacturing procedure where their key component, the engine block, covered by a 5 year warranty could lose its identity and not be traceable after the initial machining was done.

interesting stuff, and easy to see why it would have been such a big deal back then while it was going on. The time machine that is the internet will never let it die, especially with all the threads on every boating forum, but what I learned as a buyer is get the CAT survey, blow-by test, and oil samples. If all checks out, move on and buy the boat (assuming the rest of the boat is sound)

it’s easy to get wrapped around the axle by reading too much.
 
All I know is I did my homework in 1998-9, found out the facts from the Caterpillar dealer that paid for the repairs /engine replacements, on affected Sea Ray boats, excluded my engines from the list of engine models with potential problems, and then maintained my engines according to Cat's recommendations and since then have enjoyed bullet proof performance from a pair of great running engines. I'd run my boat anywhere without reservation.
 
Last edited:
All I know its I did my homework in 1998-9, found out the facts from the Caterpillar dealer that paid for the repairs /engine replacements, on affected Sea Ray boats, excluded my engines from the list of engine models with potential problems, and then maintained my engines according to Cat's recommendations and since then have enjoyed bullet proof performance from a pair of great running engines. I'd run my boat anywhere without reservation.

I’ve only put about 25 hours runtime since taking ownership but pressing the start button and running the boat with these engines is always a joy. I’m very much looking forward to extended cruises this summer. Hopefully the Canadian Border opens to recreational boat traffic but even if it doesn’t I’ll take plenty of rides to nowhere and back
 
I’ve only put about 25 hours runtime since taking ownership but pressing the start button and running the boat with these engines is always a joy. I’m very much looking forward to extended cruises this summer. Hopefully the Canadian Border opens to recreational boat traffic but even if it doesn’t I’ll take plenty of rides to nowhere and back
Hey Ryan, you list your 3126 @ 350hp... ? My 3126 are listed @ 420hp ...
 
Hey Ryan, you list your 3126 @ 350hp... ? My 3126 are listed @ 420hp ...

yep, ours are the 350HP version. I believe the lowest HP variant of the 3126 ever offered.

here they are, less their aftercoolers while they were off for cleaning

A93B3778-A276-4F6F-8242-4E5AE1FC8197.jpeg
 
Mark,

Your engines are 3126 TA's which were rated at 420hp.

Ryan's engines are marked on the valve cover as 3126 engines @ 350hp, as pictured in his post above, then he has the 3126 e's, which is the redesigned 3126 that did meet the 2003 EPA emissions requirement. They were also completely free of the valve stem and soft block issues and were de-rated to 350 hp so they replaced the 300 & 350 hp 3116 in Caterpillar's marine diesel line up.......and over the last almost 10 years have proven to be virtually bullet proof.

There is also a small printed label, usually silver in color, with the engine serial no, the engine's AR number and some timing specs printed on it and it should be located about even with the analog engine mounted gauges.


Frank
 
Last edited:
Mark,

Your engines are 3126 TA's which were rated at 420hp.

Ryan's engines are marked on the valve cover as 3126 engines @ 350hp, as pictured in his post above, then he has the 3126 e's, which is the redesigned 3126 that did meet the 2003 EPA emissions requirement. They were also completely free of the valve stem and soft block issues and were de-rated to 350 hp so they replaced the 300 & 350 hp 3116 in Caterpillar's marine diesel line up.......and over the last almost 10 years have proven to be virtually bullet proof.

There is also a small printed label, usually silver in color, with the engine serial no, the engine's AR number and some timing specs printed on it and it should be located about even with the analog engine mounted gauges.


Frank

jeez, I learn something here everyday. I’m embarrassed that I’ve always referred to our engines at 350HP 3126TA’s. The boat is a 2002, so must have been a late model to get this engine?

below is the plate Frank referred to. Frank, now I have to go research our variant but these are still MUI engines, full mechanical, yes? I’ve traced plumbing and though I’d verified all parts of the system for familiarity.

265ECA47-8A3C-47D2-BA3B-0040B5F732F6.jpeg
 
Last edited:
I’ve done more reading and also emailed CAT to check our arrangement number for specifics but I think I have a better understanding now.

our engines, if they’re 3126e, are still mechanical engines (no ecm/ecu) and have the MUI system and the HEUI (is that what it’s called on a MUI engine?) pump?

seems like the 3126e, especially at 350hp, are relatively rare birds because of the time they spent on the market between the end of the mechanical era and the shift into the C7 and ultimately the EPA “friendly” acert variant.

Btw sorry to the OP - I’ve hijacked your thread but I think it’s relevant
 
Last edited:
blow-by test during the CAT survey is the only true way to know. How many hours on the engines? If it’s more than a few hundred you’re very unlikely to have either the soft block or valve issues, they would have surfaced a long time ago if ran regularly

Blocks with FAPS stamped on them could be, but not all faps engines are soft. CAT does not have a way of telling you by SN.

if you search you’ll find many, many, threads. Most of which @fwebster has chimed in and set us straight which I suspect he’ll do here as well :)


Thanks so much guys ! Great info for me . The engine hours is LOW , showing 311 each . I've checked with 3 Cat places and that shows it could be correct . I've not visually seen the boat/engines, but have a facetime look about scheduled for this afternoon .
I'm sure this is too short of a notice for asking , but is there anything in particular I should ask to see ? IF it appears good with the facetime, definitely will do both hull and engine survey . I may ask soon if there are reputable surveyors for both in the area .
Again , thanks to all for the VALUABLE tech responses . I really appreciate your TIME !
 
Thanks so much guys ! Great info for me . The engine hours is LOW , showing 311 each . I've checked with 3 Cat places and that shows it could be correct . I've not visually seen the boat/engines, but have a facetime look about scheduled for this afternoon .
I'm sure this is too short of a notice for asking , but is there anything in particular I should ask to see ? IF it appears good with the facetime, definitely will do both hull and engine survey . I may ask soon if there are reputable surveyors for both in the area .
Again , thanks to all for the VALUABLE tech responses . I really appreciate your TIME !

The facetime thing is ok for a quick look, but surely you will be present for both survey's?
 
  • Like
Reactions: JC3
IMHO you should be there for the survey if at all possible! Things come up and decisions have to be made. Example: We surveyed a 400DA and the hull was wet. We had to decide whether to do the sea and engine survey on the spot. Being there allowed me to see exactly what area had moisture and helped making the decision to move forward with the entire survey. Good Luck. JC
 
On ≠300 hour engines, there isn't a lot to see that would indicate a problem. Look for any oil leak, or coolant leak, and look for blow by evidence of an oil mist around the crankcase vent system, or Air Sep outlet to the intake manifold.

On very low time Caterpillars, however, the most important thing to check can't be see in a video or on a cell phone.There is a critical and key maintenance task required at 250 hours.......the intake and exhaust valve lash and the injector timing must reset. This is a fairly involved process that requires special Caterpillar tools and take approximately 8 hours. You will have to probably get access to the present owner's service record at Caterpillar by having an engine survey done by the Cat dealer near to determine if this service was done by Cat.
 

Forum statistics

Threads
112,942
Messages
1,422,696
Members
60,926
Latest member
dander88
Back
Top