mack88 Posted July 5, 2008 Share Posted July 5, 2008 Hi. My 88 mack seems it wants to run warm on me.It runs at about 175 to 180 empty. I pull a 30 foot pintle with 3 axels my back hoe weighs about 24000 pounds when going down a soft road it will climb to 200 easly. when i stop it will drop down to 180 in a minute or so. I never here my fan roar when my shutters are open it has a regular clutch fan. Ther is some resenstance when the truck is cold. I had new head gaskets put on this spring. Thaks for any advice Quote Link to comment Share on other sites More sharing options...
Rob Posted July 5, 2008 Share Posted July 5, 2008 Hi. My 88 mack seems it wants to run warm on me.It runs at about 175 to 180 empty. I pull a 30 foot pintle with 3 axels my back hoe weighs about 24000 pounds when going down a soft road it will climb to 200 easly. when i stop it will drop down to 180 in a minute or so. I never here my fan roar when my shutters are open it has a regular clutch fan. Ther is some resenstance when the truck is cold. I had new head gaskets put on this spring. Thaks for any advice1988 is a little too "new" for me to be of much use but there is a proceedure to check performance of the fan clutch in service manuals. I use a hand held phototachometer to check both the crankshaft speed, and fan speed when engine is hot. The fan should turn within a certain percentage of crankshaft rotational speed at a given temperature. I don't know what engine you have, series of truck, empty or unladen weight, accessories etc. so these are "generalities" but the same principals apply. Ensuring your radiator core is clean is paramount.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
mack88 Posted July 5, 2008 Author Share Posted July 5, 2008 1988 is a little too "new" for me to be of much use but there is a proceedure to check performance of the fan clutch in service manuals. I use a hand held phototachometer to check both the crankshaft speed, and fan speed when engine is hot. The fan should turn within a certain percentage of crankshaft rotational speed at a given temperature. I don't know what engine you have, series of truck, empty or unladen weight, accessories etc. so these are "generalities" but the same principals apply. Ensuring your radiator core is clean is paramount.Robthaks Rob. It is a 350 1988 RD 688S I have had the truck for a year it had a new rad not to long before i bought it. Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted July 5, 2008 Share Posted July 5, 2008 thaks Rob. It is a 350 1988 RD 688S I have had the truck for a year it had a new rad not to long before i bought it. Be happy if it will stay up to 180 when not pulling. It should have a 180 thermostat in it. There is a way to check the clutch like Rob said . If you have a fan clutch and shutters then the engine is confused in what to do. One is heating the coolant and at the same time the other is cooling it. If it has shutters block them so they will not close and let the clutch control the heat. The way to test The fan clutch is to remove the air/air cooler or condensor off of the front of the rad so you can put a cardboard cover on the front so no air can get thru the cover except thru a hole about 4" in the front of the sensor on the clutch so the air that comes thru will blast over the sensor. Now get you a photocell tach and check the rpm on the clutch pulley and also thge rpm on the fan. This needs to be done at hi rpm and as the temp gets to about 205 or 210. The speed of the fan should be about 80% of the speed of the fan pulley. It will not be no faster than that no matter how hot it gets.This clutch does not have the failure rate that many thing. It has to be tested before it is proved to be bad. I worked at a dealer and we had to troubleshoot the proper way or the dealer would have to pay for the parts and labor if working on warranty parts so we hade to check close.Still yet i have seen guys that could look at somthing and tell you it was bad I dont think so is what i always said. test ever thing then you will know. Quote glenn akers Link to comment Share on other sites More sharing options...
HK Trucking Posted July 5, 2008 Share Posted July 5, 2008 A 1988 RD would not have shutters. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
mack88 Posted July 5, 2008 Author Share Posted July 5, 2008 A 1988 RD would not have shutters.this one has them mounted on the out side of the hood because of the air to air.I have only seen one other truck like that .So if you have a fan clutch they don't have shutters? i am a fan of Mack trucks but not to familer with the options.thanks. Quote Link to comment Share on other sites More sharing options...
HK Trucking Posted July 5, 2008 Share Posted July 5, 2008 this one has them mounted on the out side of the hood because of the air to air.I have only seen one other truck like that .So if you have a fan clutch they don't have shutters? i am a fan of Mack trucks but not to familer with the options.thanks.Those would be the "fixed" type "shutters" just for appearance.With a viscous fan drive you would not have actual opening & closing shutters, nor would a truck with a CMCAC (chassis mounted charge air cooler) have shutters because closed shutters would render the CMCAC ineffective. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
mack88 Posted July 6, 2008 Author Share Posted July 6, 2008 Those would be the "fixed" type "shutters" just for appearance.With a viscous fan drive you would not have actual opening & closing shutters, nor would a truck with a CMCAC (chassis mounted charge air cooler) have shutters because closed shutters would render the CMCAC ineffective.So should they be removed and just install a screen.Or i guess maybe just unhook them maybe just for now.Thanks for all your guys help. Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted July 6, 2008 Share Posted July 6, 2008 So should they be removed and just install a screen.Or i guess maybe just unhook them maybe just for now.Thanks for all your guys help. I cant say if it had shutters or not but i can tell you that the fan clutch will not kick in and make too much of a noise when it is engaged.Make a photo of them and post if you can. That engine should run when pulling close to 200 degress with no problem. Quote glenn akers Link to comment Share on other sites More sharing options...
mack88 Posted July 6, 2008 Author Share Posted July 6, 2008 I cant say if it had shutters or not but i can tell you that the fan clutch will not kick in and make too much of a noise when it is engaged.Make a photo of them and post if you can. That engine should run when pulling close to 200 degress with no problem.i will post some tomorrow i am on dial up so it takes awhile to post pictuers Quote Link to comment Share on other sites More sharing options...
mack88 Posted July 6, 2008 Author Share Posted July 6, 2008 i will post some tomorrow i am on dial up so it takes awhile to post pictuers Quote Link to comment Share on other sites More sharing options...
HK Trucking Posted July 6, 2008 Share Posted July 6, 2008 It looks to me like that was added on at some point. Why, I have no idea.As I said before, with a charge air cooler in front of the radiator, shutters would not and should not be used because when the shutters are closed, the charge air cooler cannot get any airflow and becomes useless.Lack of charge air cooling will lead to high exhaust gas temps, overheating and low power. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
theakerstwo Posted July 6, 2008 Share Posted July 6, 2008 I dont know why it has shutters but i would open them and make them stay open. Maybe some one else has seen this and have a reason for them. Quote glenn akers Link to comment Share on other sites More sharing options...
mack88 Posted July 6, 2008 Author Share Posted July 6, 2008 It looks to me like that was added on at some point. Why, I have no idea.As I said before, with a charge air cooler in front of the radiator, shutters would not and should not be used because when the shutters are closed, the charge air cooler cannot get any airflow and becomes useless.Lack of charge air cooling will lead to high exhaust gas temps, overheating and low power.thanks for your help i will disable it and go from there Quote Link to comment Share on other sites More sharing options...
Rob Posted July 6, 2008 Share Posted July 6, 2008 The only reason I can make for this type of setup would be to eliminate cardboard in front of the radiator in the winter to keep heat up in the cab. Those shutters do not look like anything "factory" that I've ever seen.Do you have an air, or electical toggle switch in the cab, or are the shutters automatic in operation via a thermostat in the coolant passages of the engine?Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
mack88 Posted July 6, 2008 Author Share Posted July 6, 2008 The only reason I can make for this type of setup would be to eliminate cardboard in front of the radiator in the winter to keep heat up in the cab. Those shutters do not look like anything "factory" that I've ever seen.Do you have an air, or electical toggle switch in the cab, or are the shutters automatic in operation via a thermostat in the coolant passages of the engine?Robthey are automatic usually they are closed when i start the truck but when it warms up they open.there is an air line that runs from the coolant passage to the shutters.My dad had a 1976 mack RD700 it had the shutters behind the grill,so i was kind of wondering about these. Quote Link to comment Share on other sites More sharing options...
Rob Posted July 7, 2008 Share Posted July 7, 2008 they are automatic usually they are closed when i start the truck but when it warms up they open.there is an air line that runs from the coolant passage to the shutters.My dad had a 1976 mack RD700 it had the shutters behind the grill,so i was kind of wondering about these.Hi Jook, a 1976 model would not have had a grille in it from the factory. The shutters were the grille. The opening for the hood would have been framed with a stainless steel perimeter moulding. The western trucks were different, and could of had a full grille in the form of an inverted horseshoe with a "perforated" center section. Do you have an air to air intercooler mounted in front of your radiator? You mentioned it is a 350 Mack engine and all of those with the exception of very early ones had air to air charge air cooling. The early ones used a water to air setup much the same as the 283-285 Mack engines of the 1970's, and the 300+ engines of the early to mid 1980's.As mentioned, the shutters on an air to air setup with a radiator mounted intercooler is self defeating as related to power and economy. It will help you with keeping the water temperature up in the winter time but so will a good engine thermostat. Shutters were basically obsoleted by the advent of the clutch fan whether viscous, or air engaged. Personally, I like shutters based solely on appearance but I'm not around new stuff hardly at all.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
mack88 Posted July 7, 2008 Author Share Posted July 7, 2008 Hi Jook, a 1976 model would not have had a grille in it from the factory. The shutters were the grille. The opening for the hood would have been framed with a stainless steel perimeter moulding. The western trucks were different, and could of had a full grille in the form of an inverted horseshoe with a "perforated" center section. Do you have an air to air intercooler mounted in front of your radiator? You mentioned it is a 350 Mack engine and all of those with the exception of very early ones had air to air charge air cooling. The early ones used a water to air setup much the same as the 283-285 Mack engines of the 1970's, and the 300+ engines of the early to mid 1980's.As mentioned, the shutters on an air to air setup with a radiator mounted intercooler is self defeating as related to power and economy. It will help you with keeping the water temperature up in the winter time but so will a good engine thermostat. Shutters were basically obsoleted by the advent of the clutch fan whether viscous, or air engaged. Personally, I like shutters based solely on appearance but I'm not around new stuff hardly at all.RobThanks Rob the 1976 did not have a grill it just had the shutters as a grill.Now that you mention the shutters as for winter time warm up you could be right. when i bought the truck it had a flat deck on it. i remove the flat deck on it to put a gravel box on it i noticed some body had ran cooling lines behind the cab with quick couplers. So it probally had an engine on the back for what ever job it did.They used the truck coolant to warm up that engine. Quote Link to comment Share on other sites More sharing options...
Rob Posted July 7, 2008 Share Posted July 7, 2008 Certainly hope we have been able to help you in this matter. Always a pleasure.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
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