wndrdg Report post Posted November 5, 2015 Hi, I've got a 2002 Winnebago with a 330 HP Cat that starts hard. 60K miles. The air heater does not come on until the engine temp is around 45 degrees or below. I've heard the air heater should be coming on if the engine temp is below 130. (not sure about this data). Any way, it starts hard, as if it is lean. It will fire and then quit as soon as I let go of the key. Small amount of smoke. Eventually, it will start, but I am guessing there is something wrong with the coolant sensor. When the temp got below 45 the air heater came on, but still was hard to start. I did pull a flash code of 61, that shows the engine has been overheated. Again, that might point back to the water temp sensor indicating to the ECM that the engine is warmer than it really is. I assume if the ECM knows the engine is actually at 45 degrees and not 130 it will run richer. Share this post Link to post Share on other sites
wolfe10 Report post Posted November 5, 2015 wndrdg, Welcome to the FMCA Forum. Best advice is to go by a Caterpillar dealer and have them hook up their computer to it. Should not take 15 minutes. That should identify the culprit. Could be the temp sensor, could be the intake manifold heater relay. Share this post Link to post Share on other sites
obedb Report post Posted November 5, 2015 Until you can follow Brett's advice, try plugging in or turning on the block heater. Might help you in the short run. When my manifold heater was acting up it got me started. Share this post Link to post Share on other sites
wndrdg Report post Posted November 5, 2015 Hi, The heater is working, but only when the engine it at 45 degrees or below. What temp do other people heaters come on? I've heard the heater will come on if the engine is below 130 degrees. Is this right? Dave Share this post Link to post Share on other sites
wolfe10 Report post Posted November 5, 2015 Dave, I do not have a manual on your particular engine. Please call the Caterpillar free number I posted above with your engine serial number. They can pull up your exact engine on their computer. Far better than posting what may apply to a newer or older engine, but not to yours. Share this post Link to post Share on other sites
obedb Report post Posted November 6, 2015 The block heater warms the water jacket of the engine. Your engine probably has one. 120 vac does the work but it takes several hours. If you are hooked up to RV park power or a home electric hookup you will be good to go. When in a park I turn the heater on the night before departure. Why waste energy if staying for days. It will probably give you a better start even if your manifold heater is working. The engine oil will flow better upon startup also. Share this post Link to post Share on other sites
bm02tj Report post Posted November 6, 2015 Mine comes on for a short time at 70F ambient and longer the colder it gets. About the only time it does not come on is warm restart. Share this post Link to post Share on other sites
wndrdg Report post Posted November 12, 2015 HI, I fully understand the use of a block heater, but am wanting to get the air heater working if I don't have 110V available to me. Minnesota people need easy starting diesels. It's really fun when the temp drops to -30. I am a certified Detroit person, but that was 20 years ago when everything was mechanical. I would like to update what I have found. The specs on the air heater is, it should come depending on the temp of the engine and the air temp. Combine air temp and engine temp and the spec is 130 degrees. If the air is 50 degrees and the engine is 50 degrees the heater will come on. If the air temp is 20 and the engine is 120 the heater will not come on. All that being said, my heater is coming on at lower temps. I'm guessing around 110 degrees. Not a big deal, as the actual problem that I had was more complicated. 1) Fuel pressure regulator was leaking, allowing fuel pressure to bleed down with time, meaning more cranking after sitting. Replaced that. Helped but no cigar. 2) Main issue was, I was not getting power to the air heater relay. I tracked this down to a defective 130 amp breaker. On this same panel was a similar breaker providing 12 v power to the chassis. Loose that breaker and you are done traveling. These breakers are a poor design with many failures. The air heater breaker just crumbled when I touched it. I was not able to get much help from Freightliner as they kept giving me info for the Cummins chassis. Then said the circuit breaker was inside the frame rail next to the tranny. I was not able to see the panel with the breaker on it from below, but did finally track a couple of heavy wires going straight up towards the bed area. This took some time and many trips for a gimpy old man on the ground. From the top I was able to finally locate the panel and am getting heavy duty breakers to replace the air heater and coach crappy breakers. I temporarily shorted the air heater breaker and at 40 degrees the MH started in less than 2 seconds and ran smoothly. Wheee. Dave Share this post Link to post Share on other sites
wolfe10 Report post Posted November 12, 2015 Excellent, Dave. Thanks for the detailed update. It will certainly help others who run into the same issue. Share this post Link to post Share on other sites
