Shinniu sn25 running hot

[Shenniu SN25]

Replaced head gasket, unclogged the injection pump,adjusted the timing and it's up and running. Surprised how much power this thing has. Just got to solve the running hot issue... Anyone know what the thermostat should open up at I'm thinking it should open around 180 or 190. Forgot to add replaced radiator cap with 10# cap wasn't sure what the oem was.

 

[greg_g]

Thermostat is typically either 72C (~162F) or 80C (176F). Cap is typically 0.3 (~4psi) or 0.5 bar (~7 psi).

//greg//

 

[Shenniu SN25]

Ok so I took the thermostat out ant still runs hot is it possible it's just moving the water to fast, not getting a chance to cool the water in the radiator before recirculating it... Checked the pressure in the radiator it builds 20 psi.

 

[greg_g]

Naw, removing the thermostat on an otherwise healthy diesel usually results in the opposite; running too cold. And 20psi actually sounds high. Remove the cap, start the engine, look inside the radiator. See any bubbling?

//greg//

 

[Gene :^)]

Diesel at idle usually cools itself down. Only generates heat when working. Did it reach 20psi before it even got hot? Normally any psi comes from water expanding by heat, so if pressure came up faster then it may be coming from elsewhere (like combustion).

Get this: Test Tools Inc. - Combustion Leak Block Tester, Test for Blown Head Gasket and see if your head gasket is still leaking. Most good auto parts stores or tool trucks have this tool if you don't want to wait for it in the mail. Mine was about $30 and can be used many times over.

If head gasket passes all tests, I would look at the injection. When you say it has a LOT of power, it sounds like you may be over fueling. I am not sure what effect timing has on heat but it could be an issue too. At idle does it seem to knock and bang (diesel sound) more than normal? The more you advance it the harder the knocks and bangs at idle, the more you ****** it the smoother it idles but more smoke and makes your eyes water.

Gene :^)

 

[RonMar]

If it is pushing combustion gas into the coolant, this could be warming the temp sensor artificially. You could also confirm running temp with an IR thermometer... You shouldn't see 20 PSI on the cooling system unless it was at full op temp...

 

[Shenniu SN25]

Builds 20 psi after it warms up when cold i see around 5 to 10 psi. I let it run a little longer with the gauge on it and it still seems to build past 20 then it just bypasses through the overfill hose i got plugged off to do the check. Thinking it may be the head gasket still leaking. When I first got it running it knocked very bad adjusted timing back now it runs smooth and starts easy. Head gaskets seem to be a big problem with these tractors any suggestions for getting it to hold this time. I used loctite 271 on the threads and a bottle of the silver stop leak on this install. What should the head bolts be torqued to?

 

[greg_g]

I'm not sure if I understood you correctly, but you cannot "repair" a blown head gasket. It must be replaced. And since most head gaskets nowadays are laminated with metal cylinder inserts, nothing other than clean head and block surfaces is required. Don't know anyone who'd advocate LokTite on head bolts. If they keep backing out on you, they're simply worn out. The solution is to replace them

//greg//

 

[Shenniu SN25]

The head gasket is leaking I can see it bubbling out around the head. It's an extremely cheap looking head gasket it has no steel reinforcements, you can see what appears to be paper or gasket material sandwiched between two sheets of copper looking at the gasket the old one was the same way. It cost 10 bucks... I'm thinking I didn't torq it tight enough. Any specs for this? I bought two when I found the gasket figured it would be hard to find another, so if this one has blown out I got another one. I read on another thread you should use something to seal the head bolts that's why I used loctite.

 

[jonyyuma]

Have you had the head tested for cracks? Then it needs to be checked for flatness and trueness.. what did you use for a guide on torque values for the headbolts?

 

[Rich Waugh]

$10.00 is awful cheap for a head gasket, even a two cylinder one. Are you sure it is the correct gasket for that engine? Diesels run high compression and need good quality head gaskets; generally steel is used for the cylinder rings at a minimum.

Bad idea to use Loctite on head bolts - interferes with the proper torque readings. Torque specs for bolts, unless specified otherwise, are for clean, dry threads. Bolt and hole, both. You can look up on the internet the torque specs for the size bolt you are using. Be sure to be exact - diameter and thread pitch. That will put you in the ballpark if you can't find the torque specs from the engine manufacturer. No gasket goop on the head gasket, either.

You do know that heads need to be torqued down in a proper sequence, right? Usually, though not always, it is started in the center of one side, the opposite bolt, then the next bolt on the first side, then the opposite, etc, working your way to the ends. I usually torque the bolts in sequence to about 30# less than max, then go over them again in sequence bringing them up to full torque. Others may do it differently.

The head should probably be checked for flatness. You can do this yourself if there isn't a machine shop nearby that can do it. A sheet of thick plate glass (3/8" or so) and some feeler gauges will tell you a fair amount and if you have a machinist's straightedge you can check it completely. If it is out of flat by more than .005" I'd have it milled flat. You can also have it checked for cracks while you're at it.

 

[jonyyuma]

Some diesels do use sealer on the head-bolts......To seal the threads, and most definitely have a pattern to tighten the bolts down in set values at increments...Hard to believe it does not have steel in the gasket at the cylinder, also $10.00 is very cheap?

 

[Shenniu SN25]

Haven't had the head checked, guess it could be warped or have a crack didn't see anything obvious when I had it off... I did torque it from the middle out alternating sides. I'm pretty sure it's a m16x2 stud they were torqued in two step increments to 146ft lbs i also assumed it was a grade 8.8. Gonna take it back apart this weekend if the head fix in a bottle doesn't work, don't got a lot of faith but worth a shot, dumped some bars head sealer in it just to see if I get lucky. Suppose to let sit overnight and flush the system tomorrow. I let everyone know what fixes it.

The gasket came from sun ray tractor in Ocala fl they had two in stock so I got both! Was gonna upload a pic of the gasket but not sure how to using my iPhone through the app. If interested I can send it through email.

 

[Diamondpilot]

I am no expert, never changed a head. But 146 ft lbs seems like a lot. I just rotated the tires on both my trucks and my trailers yesterday. One truck calls for 140 ft lbs, F-350 diesel. The other calls for 105 ft lbs, Nissan Titan. Both trailers called for 120 ft lbs.

Maybe I am way off but these are wheels studs that take extreem forces. I can not see a head needing that much but what do I know?

Chris

 

[Rich Waugh]

I'm not at the shop so I don't have it written in front of me right now, but it seems that 118 lb/ft was the torque setting for the head bolts on my TY395 engine, if I recall correctly.

 

[greg_g]

Y85 engine too. Book says head bolt torque range 150-170Nm. That converts to 118 ft-lb (+/- 7 ft-lb)

//greg//

 

[Rich Waugh]

Over-torquing a fastener can be as self-defeating as under-torquing. If you torque a bolt past its yield point it will stretch, but not recover, and then no longer holds tightly. In so doing, the gasket is crushed past the design point and when the bolt yields the gasket is now not properly compressed and leaks. Odds are, on a Chinese casting, you'll strip out the threads before you over-stretch a bolt, but that's not a sure thing, either.

Without knowing exactly what size and alloy the bolts were I can't say if they've been over-stressed, but if they have been then they have to be replaced with new ones.

 

[Smalljobs]

Be sure to use a torque wrench of high quality and the correct size so that your readings are in the middle of the wrench range. Using an old beat up borrowed wrench with a bent pointer is a recipe for problems. When I retorqued the head on my Jinma for the first maintenance milestone, I borrowed a high quality click type wrench from a mechanic friend in a reputable repair shop.

 

[jonyyuma]

I agree that the bolts do stretch, sometimes they cannot be reused. Thye moght can be measured for stretch, if in doubt replace. There is no sinking feeling like when a bolt gives on the last adjustment..Your setting of over 150 lbs. sounds to be very high.