Need Some Help With Water Pump Issue

[jeffl1107]

Hey Everyone,

Need some help here before I put a bullet in my head.

I am having an issue with my water pump. Its a Tri Axle Dump 97 Mack RD688S with a E7 350. Last six of Vin is 032419 if someone has any diagrams.

Ok, I drove the truck for about 1 1/2 months then my water pump went. I noticed over a period of about 2 weeks that the water temp. was reading hotter and hotter later in the day until it finally went real high and the temp light came on. So I got a replacement pump and put it on.

Ok, here is my delimna. It was about 1 1/2 weeks ago that I put the new pump on. The pump mounts on 2 places. It mounts with 6 small bolts on a housing on the front of the engine. Then there are (2) 12MM bolts that screw on the drivers side of pump to the oil cooler. Well the day after I put it on, about 7 hours after hauling, the bolts had backed out enough that antifreeze started spewing out of the gap where the pump and oil cooler come together. I saw no reason why this should happen but took the bolts off and replaced the regular washers with lock washers. Went the next day and about the same amount of time as before, it starts all over again. Bolts again backed off enough that it started leaking again. I took the pump off and checked the pump. Also had a mechanic friend come over and he said pump looked perfectly fine. We cleaned it up, put new gaskets with the high temp. permatex with new gaskets. Put the lock washers back on and also added Locktite to the bolts. Again, today it happened again only this time it cracked the heck out the housing the pump bolts on. So now I have to replace the housing.

The clutch fan that is on it, one of the blades has 2/3rds of it missing. I asked the mechanic if that is enough to throw it off balance and possibly be doing this, he said he highly doubts it. He also said how would it have lasted all the time without leaking before replacing it. I am going to replace it anyway.

So, I am trying to figure out why those 2 bolts keep backing out. There has to be somekind of vibration that is doing it, I cant figure out what else would be doing it.

Anyone have any ideas. The guy at the parts store said he thinks there should be a bracket on there but I dont have any schematics to check and see and he was not sure as the computer did not show one for my year but he thought it did have one for my year. He also told me that they did away with the small bolts that mount onto the housing. They use the same size bolts, but now they have longer bolts with a spacer. I asked if the small original bolts could have had anything to do with my problem but he said not likely since it was the 12mm bolts that were backing out.

I need to get this problem fixed so I can stop losing work. Any help appreciated.

[fjh]

Hey Everyone,

Need some help here before I put a bullet in my head.

I am having an issue with my water pump. Its a Tri Axle Dump 97 Mack RD688S with a E7 350. Last six of Vin is 032419 if someone has any diagrams.

Ok, I drove the truck for about 1 1/2 months then my water pump went. I noticed over a period of about 2 weeks that the water temp. was reading hotter and hotter later in the day until it finally went real high and the temp light came on. So I got a replacement pump and put it on.

Ok, here is my delimna. It was about 1 1/2 weeks ago that I put the new pump on. The pump mounts on 2 places. It mounts with 6 small bolts on a housing on the front of the engine. Then there are (2) 12MM bolts that screw on the drivers side of pump to the oil cooler. Well the day after I put it on, about 7 hours after hauling, the bolts had backed out enough that antifreeze started spewing out of the gap where the pump and oil cooler come together. I saw no reason why this should happen but took the bolts off and replaced the regular washers with lock washers. Went the next day and about the same amount of time as before, it starts all over again. Bolts again backed off enough that it started leaking again. I took the pump off and checked the pump. Also had a mechanic friend come over and he said pump looked perfectly fine. We cleaned it up, put new gaskets with the high temp. permatex with new gaskets. Put the lock washers back on and also added Locktite to the bolts. Again, today it happened again only this time it cracked the heck out the housing the pump bolts on. So now I have to replace the housing.

The clutch fan that is on it, one of the blades has 2/3rds of it missing. I asked the mechanic if that is enough to throw it off balance and possibly be doing this, he said he highly doubts it. He also said how would it have lasted all the time without leaking before replacing it. I am going to replace it anyway.

So, I am trying to figure out why those 2 bolts keep backing out. There has to be somekind of vibration that is doing it, I cant figure out what else would be doing it.

Anyone have any ideas. The guy at the parts store said he thinks there should be a bracket on there but I dont have any schematics to check and see and he was not sure as the computer did not show one for my year but he thought it did have one for my year. He also told me that they did away with the small bolts that mount onto the housing. They use the same size bolts, but now they have longer bolts with a spacer. I asked if the small original bolts could have had anything to do with my problem but he said not likely since it was the 12mm bolts that were backing out.

I need to get this problem fixed so I can stop losing work. Any help appreciated.

The longer bolts with a spacer is an update as the bolts used to break on some models! The fan blade is likly most if not all of the problem here youalso notice the fan hub itself weighs a ton thats the rest of the problem but you can't change that,So My bet is the fan blade!also on some models there is a 1/4 inch metal bracket that bolts to the corner head bolt lh front of the engine if that bracket is missing this may add to your problem.

[jeffl1107]

Thanks for the info. Couple of questions? First, you said the the fan weight on the hub can be changed. Was wondering if you could elaborate on that. Do I get a different model or do the new fans just weigh less.

And second, do you know how I would find out if my particular truck calls for that bracket. The guy at the parts place I go was kind of unsure.

Thanks

[fjh]

Thanks for the info. Couple of questions? First, you said the the fan weight on the hub can be changed. Was wondering if you could elaborate on that. Do I get a different model or do the new fans just weigh less.

And second, do you know how I would find out if my particular truck calls for that bracket. The guy at the parts place I go was kind of unsure.

Thanks

No Bro I said , hub itself weighs a ton thats the rest of the problem but you can't change that,Get a new fan an check to see if the upper bracket is missing!I am not sure on your truck either but if there is a nub sticking up on the housing with a threaded hole in it it is lkly to have a bracket on it!

[mackmech]

No Bro I said , hub itself weighs a ton thats the rest of the problem but you can't change that,Get a new fan an check to see if the upper bracket is missing!I am not sure on your truck either but if there is a nub sticking up on the housing with a threaded hole in it it is lkly to have a bracket on it!

The company i work for had same problem on a E7 460 sometimes several bolts fell out within a few minutes. we changed parts one at a time trying to find problem,first went to plastic fan which is an update,then lower pulley and finally harmonic balancer which cured issue. the bracket is very important try to find it and make sure itis there. also when bolting down pump hand tighten all bolts then tighten oil cooler bolts first then water pump bolts if not housing will crack every time. also new water pump with pulley work better for us. dont know if this will help just some ideas to consider.

[jeffl1107]

Hey guys,

thanks for both of your comments. They will help.

Yeah, sorry about that, came back and read it again before your post and realized you said, "CANT". I got everything stripped off about an hour ago. Was not that bad taking off. Got a couple of questions though for either of you.

First, it must have been the original housing because there was "NO" bolt hole in top of housing. But the new one does have a threaded bolt hole. They did give me a 1/4" bracket. But, I cannot see where it would bolt onto the head. It has 3 bolt holes in the bracket. It has 2 bolt holes top to bottom and then around the middle is a portion sticking out that has 1 hole, I guess to the housing. But, the paperwork they gave me with the recall stuff on it, says that only the CH model can accept this bracket. I have an RD. Will this not work then?

I got everything new. Pump, housing, bolts, gaskets, belts, etc. The new fan is metal that they gave me. And yes, I did see the report that says if this issue continues, to replace the vibration dampner. I dont know how expensive they are, but I am wondering if I should just get that also. Parts wise, and wallet wise, I can afford for this to happen again. Not only did it cost me almost $600 in parts, but I cant afford to take that hit again and more importantly losing out on work.

Guys never called me back from Mack today for price, so do any of you have a guess what the harmonic balancer goes for???

[rhasler]

Hey guys,

thanks for both of your comments. They will help.

Yeah, sorry about that, came back and read it again before your post and realized you said, "CANT". I got everything stripped off about an hour ago. Was not that bad taking off. Got a couple of questions though for either of you.

First, it must have been the original housing because there was "NO" bolt hole in top of housing. But the new one does have a threaded bolt hole. They did give me a 1/4" bracket. But, I cannot see where it would bolt onto the head. It has 3 bolt holes in the bracket. It has 2 bolt holes top to bottom and then around the middle is a portion sticking out that has 1 hole, I guess to the housing. But, the paperwork they gave me with the recall stuff on it, says that only the CH model can accept this bracket. I have an RD. Will this not work then?

I got everything new. Pump, housing, bolts, gaskets, belts, etc. The new fan is metal that they gave me. And yes, I did see the report that says if this issue continues, to replace the vibration dampner. I dont know how expensive they are, but I am wondering if I should just get that also. Parts wise, and wallet wise, I can afford for this to happen again. Not only did it cost me almost $600 in parts, but I cant afford to take that hit again and more importantly losing out on work.

Guys never called me back from Mack today for price, so do any of you have a guess what the harmonic balancer goes for???

The bracket is for the CH model. It attaches to two head bolts which would have holes threaded into the top of them. I don't think it will mount up properly on an RD due to the center line of the fan being located differently on the two chassis.

[jeffl1107]

Ok, that is what I thought. If you read my post up top, then you know the problem I am having. Was wondering if you knew approx. how much a harmonic balancer costs? It sounds as though I am going to need to replace that from what was about the other person having the same problem with their truck and it ended up being the problem.

[fjh]

Ok, that is what I thought. If you read my post up top, then you know the problem I am having. Was wondering if you knew approx. how much a harmonic balancer costs? It sounds as though I am going to need to replace that from what was about the other person having the same problem with their truck and it ended up being the problem.

Definate possibility on that balancer, I never ran into that problem on a mack , but I did on a binder dt466 kept throwing belts tried everything with that too, then took a stab in the dark with the balancer which cured the problem!

[jeffl1107]

Ok so I guess my last question is, after all the new parts are installed, NOT including the vibration dampner, there is no way for me to somehow test it to see if the missing fan blade was the culprit. I am sure the vibration dampner is not cheap and I dont want to have to get one and replace unless necessary. But, I also dont want to start running the truck and have a repeat of the housing breaking and having to do this all over again. Any suggestions???

[rhasler]

Ok so I guess my last question is, after all the new parts are installed, NOT including the vibration dampner, there is no way for me to somehow test it to see if the missing fan blade was the culprit. I am sure the vibration dampner is not cheap and I dont want to have to get one and replace unless necessary. But, I also dont want to start running the truck and have a repeat of the housing breaking and having to do this all over again. Any suggestions???

Sorry Jeff, I missed the part about the fan in the original post. It might not have been the inital problem but it will only add to the problem. It isn't pretty when they come apart at high speeds, so I would say you did the right thing replacing it. I'm not sure of the cost of a new dampner. I would check all of the items driven by the belts (alternator, A/C compressor) for loose pulleys or mounting brackets and hardware. You can make a visual inspection of the dampner as well. Look for signs of fluid leaking from it, and for cracks, dents, and bulges in the dampner case.

[JerryB]

also when bolting down pump hand tighten all bolts then tighten oil cooler bolts first then water pump bolts if not housing will crack every time.

I know a die hard who learned that the hard way........

[jeffl1107]

So how hard is it to replace the vibration dampner for the DIY. I have done 1 on a car engine in the past and i consider myself pretty mechanically inclined. Only problem I guess would be finding a puller and install tool for it. Local Mack dealer does not rent them. I called a few service places and they said the RD is the hardest one to replace and they were looking at around 7 hours time. There looks to be plenty of room in front for the tools to pull and replace and do you mess with the seal in front of crank at time.

[rhasler]

So how hard is it to replace the vibration dampner for the DIY. I have done 1 on a car engine in the past and i consider myself pretty mechanically inclined. Only problem I guess would be finding a puller and install tool for it. Local Mack dealer does not rent them. I called a few service places and they said the RD is the hardest one to replace and they were looking at around 7 hours time. There looks to be plenty of room in front for the tools to pull and replace and do you mess with the seal in front of crank at time.

The dampner doesn't require specal tools to remove or install. It should be held on to the crankshaft hub with 6 10mm bolts. The dampner slides over the end of the crankshaft hub and has no contact with the front main seal. They can be tough to get off due to rust build up between the hub and dammpner but with a little work usually comes off without too much trouble.