engine won't come up to temp.

[240b]

I've a 4 cyl cummins which won't heat up over 130 F  I've put two new thermostats in, one OEM one NAPA.  checked the gauage against another which is known to work, both show the same thing.  I've the same motor in my loader and it heats up to 200 the stat opens and it stays at 180 the rest of the day.  I am stumped..... 

[bushmechanic]

What temperature is the thermostat rated at?Should be written on it somewhere,you may be installing a lower opening thermostat and that may be working just fine.Check with Cummins and see what temp is supposed to be there or John Deere on the Timberjack side of things.

[sealark37]

Considering what you have already checked, I would zero in on the probe and wire that transmits the water temp to the gauge. The probe may be damaged or defective.  It may be installed at the wrong location or isolated from direct coolant contact.  Regards, Clark

[H60 Hawk Pilot]

Let's Go Over This:

1. Changed out with old thermostat with two new thermostats.

2. Verified the true temp. is >> 130 deg. << with a known good (2nd.) gauge that reads (100%) correctly.

Thermostat Testing, take a known (accurate) gage and (gage bulb wired in place to put bulb in water) heat up a small pail of water with a hot plate or other heating source. The thermostat will be fully open at the marked temp. on the gage i.e. 175, 180, 195, etc. .  Most thermostat's (failed) do not open and this includes thermostats that are brand new out of the box.

In your case, you've replaced two thermostat's and still (if they were bad) and should have been over-heating (most common failure). However, you're (new) thermostats went wide open and stayed there and caused low coolant temperatures. This type of failure is rare and almost impossible with (2) thermostat's changed out.  I wonder a little bit about your testing gauge ? Do you think it's (really) 100 % accurate, if so.. then OK.  I have chased problem's that were never broke in the 1st place, so make sure your test gauge is correct.

I ran into a engine that had a coolant heater on it and it circulated water through this piping and prevented the engine from heating up correctly. So check the engine out for any type of coolant piping that can by-pass the water and cause the underheat problem.

Also, did you change anything on his engine ?  Did you add or remove anything ? If you did, check out what has been changed and what effect it has made to your cooling system. Does the fan run all the time ?  During cold weather, a fan that runs all the time will cause low coolant temperatures.

Another simple check is to feel the top hose and it should be about 10 to 15 degree's below the thermostat setting after it warms up to it's operating temperature.  I've recorded this type of temp. with my heat gun and it's really handy for checking all types of engine problems.  I use it on -- gear boxes  &  brakes, rear's, etc., just a great tool to have in your tool box. I've used it lot's of times to watch the therostat open and shoot the top house and se the temp. come up. I've seen it the other way when the therostat remained closed and top hose remained cool and No flow.  

Closing:

Best guess (if temp. gage is correct) is >> by- passing of cooling system...the coolant is going around the thermostat and allowing eng. temp. to remain at 130 deg. .  The 2nd area is the oil cooler/ water cooler. I've seen failure's here where the cooler failed and exchanged one into the other. However, this is usually found as  Oil in the water (coolant) and water in the oil. When the engine is running >> oil is pumped into the radiator. When the engine shut's off.. pressure remains in the radiator and then back flows into the oil. You will see the oil turn to a soupy mix... a grey/ white colored paste. I have seen it mix only one way as well but this a rare case, can cause low temp's. too. When the cooler themostatic valve stick's open... the coolant is routed around the engine. This malufunction (yep, back into coolant by-pass) causes low coolant temperature.    

Remember, that all the thermostat does... keeps the coolant inside the engine to warm the coolant up to correct eng. temp. .  After this.. the thermostat open's to route the coolant through the radiator. The radiator does it job to cool the coolant, off load's the heat and returns cooled water back to the bottom of radiator, then pulled back into the engine from the suction side of the water pump.  You may not need a coolant operation class but..  I threw it in for free. If I can see how stuff works in my mind.. I can fix it, otherwise, it's just hit or miss (for me).  

Avery

  

[240b]

I have not changed anything and there is no cab heater to act as another heat exchanger. I have been running it with the radiator blocked off for three weeks-- just to get though the winter.  the stat is 180F that is the cummins spec.  No white smoke or oil in water/water oil.  I am starting to think it is a head gasket issue..   I am calling the Cummins guy in the am.  This thing has 8900 hrs on it and aside from oil changes and a injection pump rebuild has never been worked on... and two stats and the water pump I put on today.    I hope this is something simple.. 

[H60 Hawk Pilot]

Are you 100% sure that your temp is 130 degree's ?

I've never seen or heard of a  head gasket that caused a under-heat condition (maybe it will but weird).  I've seen external and internal coolant leakage from head gaskets. The most common failure is the pressuring of the coolant system from cyl. compression leakage. The head gasket failure will bleed into the coolant system and push coolant out the the radiator over flow.

Send me the model ________ of the 4 cyl. Cummins. What year is it __________.  

I don't need the S/N.  I'm going to bring this engine up and look at the cooler system and piping.  I worked for Cummins and know all the bigger engine's very well. The little (4BT, etc.) engines were not around yet; worked for them in the mid. 70's.

Avery

[SPIKER]

I have 2 ford thunder birds, in the last 2 years I have put in 5 or 6 thermostats in the two of them and they keep doing the same thing.   works once or twice then fails open...   most were/are auto zone $)&% that and the last one is a MR Gasket high performance that has done the same thing.   I know they worked when I put them in, as they both came up to temp once or twice then stuck open.   two of them were those junky ones which are designed to stay open if it gets too hot.   the others seem to have weak springs or poor stampings as the get wedged or cocked and are done.   not sure if the cars just develops too much water flow or what but it has been happening to me...   I verified my temp readings using heat gun on the manifold & water neck at 130~145 after 20 mile drive.   It is hard to get the reading though as it warms up as it slows down some.   I have the rad blocked off with cardboard and still hardly gets to the warm mark.   been a COLD winter driving the one the other I parked as too many holes to keep the frost bite away...

mark

[H60 Hawk Pilot]

Spiker

I'm with you 100% on the cheap therostats. I had a problem with my 02 Camaro and changed it out with a Fail Open design. My autozone srat. worked fine but was the best one they sold.

My post above was directed toward diesels and the OEM stat's. are (sometimes) junk as well. Inspection of a stat. that's miss-behaving is important too. If the stat. has been in service for awhile you'll see the rub/ wear marks on it. If I see that it's been
in-service for a long time I.. just pitch it. One other point is the stat. that opens half way or so and causes a over heat in hot weather and/ if your working the engine fairly hard (over temp.).

My friend bought a new ($1,800.00) radiator because he thought his stat. was good. He just had his engine rebuilt for $ 11K and it had a new stat. installed during the rebuild.. so had to be good. The new stat. failed closed and this happens all the time with new stat's. .  He installed the new radiator, took the truck for a test ride and it over heated... big time. He called me from the side of the road and said.. what's wrong with this **$%&* engine now.  I asked him to touch the top hose... is it hot or cold or what. He checked it and said, it's just a little warm. I told him the 2nd time... go buy a new stat. and install it.. problem will be fixed.  He's still mad at himself for replacing his rad. ($1.8K) that was just 3 years old and 100% good to go.

The moral of this story is to troubleshoot properly and find the problem. Don't throw expense parts at the engine and just hope you'll get lucky. Also, don't tear a engine all apart and have parts thrown around everywhere. Run the engine as necesaary and fine out what is wrong before it's taken apart. The one exception is  low oil pressure problems. Don't run this engine at all if you think it (really) has a oil feed/ very low problem i.e. knock, no oil press, etc. . 

Avery
 

[CX3]

Question-what are some disadvantages to running an engine too cool??

[SPIKER]

running engine too cool can cause excessive wear on rings & valve stems it also can cause issues with new computer controlled cars as they keep running rich when the temp is low (thinking cold engine needs additional fuel.)   Additionally it can cause buildup of water, combustion gasses in the oil & carbon up of the heads exhaust system.   the CATs also can not get up to temp as well as they should when running cold. 

Mark

[H60 Hawk Pilot]

Don't Do It for a Long Period of Time.

Running  a Diesel Below it's Design Temp. is a Bad Thing it.. Shorten's Engine Life.  A Diesel is a Heat Engine by design and operates poorly at lower coolant temperatures .

The Bad:

Fuel slobbering in cyl's. & washing down the cyl. walls ... causes a lack of lube on walls. This wash down effect will wreck rings and turn them into junk in about 1000 to 1500 hours of running too cold. You will have an excessive build up of (partly) unburnt fuel (combustion) by-product's pushed pass the rings and into the oil pan. Carbon builds up at a much (valve's, piston's, etc.) higher rate, this will freeze the rings up (carbon) in the land groves in about 1500 to 2500 hours of operation. I get these different engine hours from Cummins, I was a Warranty Mgr. there. I remember some of our engine's that ran too cool. These engines started failing at the hour range(s) .. list above. The wider hour range is dependent on just how cool the engine ran.  The carbon build up is much higher on a 120 deg. than a engine that was operating just out of the correct temp. range.. say 150 deg. or so.

The worst case of slobbering fuel was in  855 CI Cummins, 350 HP, that was installed in a big drag line as a swing engine. The engine was only up to speed for a short time ... to turn the drag line and then right back to idle again. Consequently, the engine did not come  up to speed for very long and ran too cool, ran very cool during the Winter in PA.  We had several of these 855 swing engine's develop problem's.. as listed above. Cummins came out with a muti-fix solution. We went out and changed the following items: cam timing to reduce the sobbering effect, increased operating temp. by 10 degree's to 195 deg F. {I think). We installed an air cyl. controlled shutter system on the radiator (temp. controlled) to control air flow through the radiator. The rad. shutter sys. was really needed for freezing temp's. in the PA winter and did a great job. Yep, that fixed the (running too cool) engine problem.

The engine problem that you have can be found (100%) with a little more troubleshooting. I'd love to be there with my heat gun and scan this engine from the minute it starts up. My heat gun is accurate and not china junk. I'd make sure that the eng. is serviced correctly and all levels were on the line., belts tight, eng. ready to run. I'd fire it up and start scanning in about 5 minutes. I verify that the top hose was still cool and showed very little flow. If possible, I'd look down the radiator fill port and watch for or verify No swirl or coolant movement as yet (eng. block stat. is closed).  In (about) 15 minute's, I'd feel the top hose, it will be a little warmer and stiffer with coolant flow starting to flow to the top of radiator.

Let me stop here.. if the stat. is open (failed open) from the moment you start.. everything I just mention (sentence above) will happen right-a-way.  

Normal engine operation continued... the top hose will get warmer & warmer and show an increase in surface (increased coolant flow) tenson as you squeeze it. You can see coolant flow (looking down rad. filler neck) water movement... more n' more water movement.  If you had temp. scan tool, you'd hold the scan beam close (about 9 inches) and take readings on the thermostat housing where the top hose connect's.  Scan the hose up to the point where it connects to the top of the radiator. From here, scan the top of the radiator and go from top to bottom. Watch the coolant temp. drop as you move downward on the radiator. Scan the bottom hose as it came off the bottom and connects to the engine. We're checking the temp. as the coolant is drawn back inside the engine on the suction side of the water pump. All this time,  I'm looking for the heat to increase and be lowered (normal range) as I scan the engine (as described).

When the engine reaches it's operating range temp., whatever it is ___ ? the scanned temp. at the thermostat housing (or temp. sensor in eng.) should match the equip. gage within 5 degrees.  I say this... if you know the accurracy of your testing tool (scan temp. gun). I have a good manual temp. gage that has a long stem. I put in the radiator filler neck (when I can), I do this to back up my scan tool as well.

I mentioned that most of our engines have therostatic cooler valves and flow coolant as needed through the cooler. When you start the cooler valve is closed to allow the oil to heat up properly to operating temp. (oil wise). After it reaches the right oil temp.. the thermostat opens at the cooler valve. When the cooler thero. valve opens... coolant flows through the oil cooler and drops/ maintains oil temp. to the correct oil temperature.    

Here's the deal.. if that cooler valve sticks open, the engine will have added coolant flow and cool the engine... more than normal. It's like adding a add on cooler to the engine for more of a cooling effect. Also, your closed cooling (eng. starting up cold) system will be screwed up with coolant running freely to engine cooler.  I don't know the exact plumbing of your engine but this does happen on Cummins engines. This was common place on some of the older Cummins engines (stuck open cooler thermo. valve).

If you suspect this is happening on your engine.... scan or feel the lines going to the cooler. The lines should be cool and get slighty warmer and warmer as the engine warms up. However, newer engines have the coolant feed through the block and harder to verify the temperatures. You want a very small temp. change at the cooler.. which means the valve is closed as it should be upon start up. The scan tool will give you a good idea when you shoot the cooler housing (as described above). Also, some coolers draw off the bottom rad. hose feed from the radiator. If this engine is plumbed this way.. your going to be screwed up and running cool (valve stuck open).

You mentioned that you have a 2nd engine and running at the correct temp. .  I'd use this engine as my touch and feel engine and compare data to the cold running engine. This (1 to 1) comparison should speak volumes and lead you to the problem in short order.


Avery

    

[John Woodworth]

Just a thought are you running a push fan? if so try a pull fan and see if that helps, yuu will be retaining all that rad. heat and maybe that will help.

[240b]

Hawk Pilot  it is a 4bta ,built in june 1995.....   talked w/ cummins dealer whom I know well and is a very through guy this am he gave me another test to do and I am thinking about taking the stat out of my loader which is proven to work and trying that.(I am really good a changing them now.)

[240b]

Hawk pilot I just reread your older post about the oil cooler.. being stuck open.. Iam going to run out and check this.
Also could the after cooler be causing this problem?

[H60 Hawk Pilot]

What is the Next Test from (suggested) Cummims ?  I worked on diesels for a long time and can't think of another test to perform. I'm asking because I like this (diesels) business and can still learn new tricks of the trade.  

Taking the known good stat. from the other eng.  might be worth a try  but I'd do that last.

You have  2 stat's that are new and should be returned if they are bad.. right out of the box.  All parts (small parts) like these stats. have a  90 to 180 day warranty.

I'd test them both at the same time. Make it simple, find a small metal pot, put enough water in it to cover stats. & 1 inch. more, heat it on a stove, place the stem of your therm. (wired in place if necessary) in the pan. Turn the heat on and at a higher heat at first. When the thermometer shows 130 or so... turn the heat down a litttle so that you have time to see the stats. movement (at a slower rate). Have them facing you so you can see them (clearly) openning as you look down on them.

You have one from NAPA and the other is OEM.  Know which is which in this test, so you can put them in the right box for return (if bad). If you don't have a thermometer handy.. consider these sources.. mama's cooking therm., buying AC checking therm. at Autozone or NAPA for around $10.00 bucks. Buying a manual temp. gage at NAPA or ? for $ 16.00 bucks or so. You will get your money back for these one or two stats. if they are bad. More important, will answer your question about bad stats. Most important ... You did Not mess with a good running engine and got your money back to boot.

Back to the last part of your test. The stats. will begin to open at 130 to 150 or so. This is the key.. they will be fully open at 180 deg's. or what temp. they're marked at. Take the water to (just) a boil at 212 deg. F. and verify that they're fully open at the temp. they were mark at, say 180 or whatever.  I say it this way.. you should see zero (nearly) movement to the stat. from it's .. fully open position at 180 Deg. as you do at a boil temp of 212 deg. >>>  No More Movement !  If you did see it open wider, it's out of calibration and faulty. This stat. should have been moving later than it should have when the water was at 130 or 150, it was bearly cracked open or not at all at 130 or 150 deg. .

If I did not have a temp. gage, I could tell if I had a good idea about the stat. by doing the test as outlined above. When I'm just starting to boil, the stat. is fully open and was fully open a short time before this (boil), when the water is just getting hot at 130/150 deg., the stat. is starting to open (cracked open) and opens at a progressive rate until fully open {that simple).

Checking stats. is not difficuult and takes just a few minutes.  No... this simple check is not a 100% about 95%. It's described this way in more engine repair manual then I can count. The 5 percent error is for a stat. that hang's up but did not do it this time (your test).  If it hangs up, you'd be over heating, not underheating. The other error is opening too quickly and causing a underheat. (eng. running cool). Your need to watch these stats. and see that they are just cracked open and showing movement at 130 to 150.  If the stat. goes wide open when the water is not that hot (130/150).. it's No Good. The fact that your're checking both stats. at the same time is noteworthy.  The thermostat truth (good/bad) will be right in front of You.

Closing: My little mech. voice say's that both of these stat's. are not bad. I'd rather be wrong then right, let me know. I hope that your equip. gage(s) are accurate. You can have two bad gauges and be wrong and cause a lot of work for yourself. Ask me how I know that. It never happened (was lucky) to me but did to other mechanics and folks I know, Yep, bad tests (gage's off) and they tried to fix something that was never broke and it happens this way all the time.  I'm really liery of electric gauges when I troubleshoot oil pressure and temp. problems. I have a master set of test gauges and they are 100% right on. I've been down this road before... being misled by electric gauges that are known to be in error.. more often than not.

Just.. going full circle and sharing information for your benefit and my helping hand is out to you.  

Avery

[H60 Hawk Pilot]

The After Cooler can not cause this problem of running too cool.

You're taking 180 deg. coolant and running it through the after cooler and cooling the turbo (pressurized) air that's blown into the cylinder's. The coolant exchanges it's 180 deg. coolant with 270 deg. (or so)  turbo charge air going in the cylinders. This air exchange drops the 270 air temp and gives better eng. performance and reduced cyl. temperatures. Packs more air in the cyl. to boot; always looking for cooler air to be pushed into a cyl. to get the best Horse Power.   

The common failures are: leaking aftercooler, the coolant drips into the cyl's or leaks externally as well. You can blow a gasket and lose turbo boost, the engine will smoke big time and carry on when you go to 1/2 throttle and up, not enough turbo boost to burn the fuel.

If you lose coolant through the after cooler, the engine will overheat due to low coolant level for the engine.   


Avery

[kiko]

It is propably a coolant flow problem. The coolant is spending to much time in the radiator. If stats check out, look at water pump fins. The fins are metal but could be damaged.  The water pump is easy to remove. Drain coolant , remove belt, take the two water pump bolts out (10 mm socket), remove pump. It has a rubber o-ring seal so this can be done without need of a new gasket.

[H60 Hawk Pilot]

I've seen the water pump blades get beat up by something getting into the coolant system and messing the WP blades up. The result was decreased flow and over heat when the engine was at a higher power settings. The thermostat can not see the condition of the WP blades and will let water out when it reaches the stat. temp. of 180 or so. Otherwise with the stat. closed. .. the coolant goes around and around in the block and never see's the radiator until it opens (general theory).

I never say never and you have a point to share and seem to know this engine... and what is what.


Avery

[kiko]

Water pump check is so easy why not eliminate it? With metal fins it is unlikely but have seen this same thing on jd power tech engines that have plastic fins that were half gone.  Cummins troubleshooting goes as follows:

                                                             Coolant temp below normal
1. Air flow across radiator excessive 2. thermostat, broken, damaged, contaminated or not sealing 3. Temp sensor or guage malfunction  4. coolant not flowing by temp sensor.

A closed thermostat does not block all flow through radiator. There is a weep hole in the thermostat itself. A manuel temp gauge would be the best diagnostic tool as the electrical temp gauge/ sending unit combo must match each other. The temp sender changes its resistance to ground as temp changes. So, swaping from another machine requires swap of gauge and sending unit to be correct. The engine could not be grounded well to frame. There could be thread tape on the sending unit that inteferes with the unit ability to ground properly.  Theory as he says.

[H60 Hawk Pilot]

Looks 100% to me (your Cummins Troubleshooting Guide).

All engines (most)  have the small vent hole to flow a small amount of coolant from the thermostat head, the hole size is about 1/8 to 3/16 in dia. and have never seen one bigger than 1/4 in dia. in small engines. It's just a vent and never enough flow to over cool a engine under normal conditions. It may be enough in sub zero conditions with the fan running as well. Some engines have a anti-aeration line that runs off the block and feeds to the top of the radiator, just 1/8 D. in size.  You mentioned the excessive air flow over the radiatior and that's a real deal in cold weather.  I've blocked off all the  air flow through the rad.  with card board to get the eng. up to temp in -25 deg. cold.

I  Buy the part about the elec. sendors and match up to the indicators (matched set). The thread tape is something that I did not think (no grn.) about.  I've said,  all along that this over cooling problem may not exist. To check this engine with a (known accuracy) manual reading temp. gage and verify that your have a engine that's really running too cool (130 Deg.). 

Hell's bells, I'd stick some card board in front of the rad. & see if the temp came up then.. how simple of a check would that be.

Avery