cm870 wont crank hot

[Brock]

With good oil pressure I'm going to not assume major engine issues and believe you have 2 seperate simple issues.......

http://rawze.com/forums/archive/index.ph...420-2.html

Oil cooler and oil thermostat for your oil temps.

As far as not starting hot, I dont really care that 2 shops tested the starter, what I care is did they test it when the engine wouldn't normally start?

Example: I brought my ecm to Cummins to bench test, they said it was good, I had already verified it was not so i told them to test again, they said it was good again..... I told them to get it hot and keep bench testing it as I'm paying for the tests so stop whinging.

Finally it failed once warm and kept failing.

I've seen this so many times over the years and your starter could be the same..... heat causes metal to expand, bearings seize up while cooling and wont let it engage.

Barring the engine while warm may give you a idea. I'd properly test that starter or just swap it.

[SIDE_SHOW]

(10-13-2019 )Brock Wrote:  With good oil pressure I'm going to not assume major engine issues and believe you have 2 seperate simple issues.......

http://rawze.com/forums/archive/index.ph...420-2.html

Oil cooler and oil thermostat for your oil temps.

As far as not starting hot, I dont really care that 2 shops tested the starter, what I care is did they test it when the engine wouldn't normally start?

Example: I brought my ecm to Cummins to bench test, they said it was good, I had already verified it was not so i told them to test again, they said it was good again..... I told them to get it hot and keep bench testing it as I'm paying for the tests so stop whinging.

Finally it failed once warm and kept failing.

I've seen this so many times over the years and your starter could be the same..... heat causes metal to expand, bearings seize up while cooling and wont let it engage.

Barring the engine while warm may give you a idea. I'd properly test that starter or just swap it.

going on 3rd starter in a year..... on my way to harbor freight right now to get a 3/4 ratchet and try barring it over... im driving the truck over there o its good and hot when i get home...

if the cooler was bad would it not have high oil temps at idle? it would come down to 1 degree delta at idle? im not sure ive never had a bad cooler on a cummins... i know ever other engine ive had a bad cooler usually has big deltas at all times... not sure on a cummins though

[Unilevers]

bar it over after a hot shutdown. If it truly is that hard to turn that the starter cant do it - you will not be able to do it with that 3/4" ratchet. If thats the case pop the covers and remove the rockers and try again - look for any spun cam bearings while there. then injectors and try again. If it still binds remove the pan and try again while someone watches - see what hole is binding up. if you cannot pinpoint it start taking bearing caps off rods until it free's up - you can see if its a main binding easily.

finding hard spots in engines isnt rocket science. I personally think its probably a spun cam bearing or a starter/voltage issue.

[SIDE_SHOW]

(10-13-2019 )Unilevers Wrote:  bar it over after a hot shutdown. If it truly is that hard to turn that the starter cant do it - you will not be able to do it with that 3/4" ratchet. If thats the case pop the covers and remove the rockers and try again - look for any spun cam bearings while there. then injectors and try again. If it still binds remove the pan and try again while someone watches - see what hole is binding up. if you cannot pinpoint it start taking bearing caps off rods until it free's up - you can see if its a main binding easily.

finding hard spots in engines isnt rocket science. I personally think its probably a spun cam bearing or a starter/voltage issue.

i just got it home and tried barring it with the ratchet and a pipe and i could not get it to budge...

i will tear into the over head tomorrow and see what i can see...

[Rawze]

you guys might be waay over thinking it too ...

U know if the fuel bleed-off orifice for the injection timing circuits is going bad in the IFSM, it can cause hard starts until the engine cools off.

it is mentioned starting at 0:58 in this video. It goes on to mention the 0.008" bleed-off orifice that prevents hard starts and excess pressure once the engine is shut down...
https://youtu.be/_WeiDC6S8Lw

Just a thought.

If it is this orifice, or circuit is clogged up in the IFSM, then it would be also highly likely to contribute towards high oil temps too, as the injection timing would get screwed up as well from improper fuel flow quantities to the timing circuits.

Maybe pulling off the entire FISM, dissembling it entirely and cleaning all the valves, check valves, cross channels, components, etc. and that orifice (there is an access plug in the bottom of the IFSM to get to it from what I have gathered, though I have not done it). -- or replacing the entire thing with one off another truck that runs good as a test.

==== Aside from what I have described above being the entire culprit, the next thing to do is ...

Once the hard start issue is resolved ... if high oil temps persist as a separate issue ...

-- as far a the high oil temps, he needs to verify the oil temps are accurate within a few degrees using a temp gun (on the oil filter perhaps if need be like others mentioned). Replace the oil temp sensor if necessary.

Then the next step would be to replace the oil cooler and thermostat. it could be that the thermostat is going bad, I have mentioned that to him when he was here, and it also can be that the oil cooler itself is partially plugged, or anodized internally and unable to do a proper job.

Personally, I would point my finger at the IFSM orifice and its bleed-off circuit. That makes the most sense so far. That bleed-off line is only 0.008" big and VERY easy to get clogged up, especially if the truck has ever had algae issues, or some moron was not changing the fuel filter often enough on it, or was pre-filling the fuel filter with possibly contaminated fuel. Cummins says to always put the fuel filter on dry and clean, let the electric lift pump fill it before starting engine.



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[alamow]

Rawze suggestion regarding the releasing of fuel pressure after shut down would be worth pursuing. Fuel pressure test after shut down?

I had a similar starting issue. Went through 4 starter motors, cables were replaced. Engine was rebuilt with a remanufactured head. Starting fault returned after a few months and the cause was a leaking injector cup in the head. Would start fine when the engine cooled.

Brand new head and never had a starting issue again.... until the engine dropped a liner and put three holes in the block.

Aftermarket main bearings were used during the rebuild and they were toast after 11 months/240,000km.