MM 602 coolant in oil

MNGB

Well-known Member
Hi all, asking for my brother he bought a MM 602 earlier this winter it runs good looks fair to good had been sitting for some time anyway hes used a little bit and notice coolant is getting into the oil it does not miss and runs good he's wondering if it could be the water pump seal leaking?
GB in MN
 
More than likely. There is a weep hole in the bottom of the casting between the water pump and the timing gear area where the water is supposed to leak out in case of a seal failure. But this is always plugged up with grease from greasing the pump bushing. Take a piece of baling wire and dig around up in the hole and see if you get any water drops. If so you probably found your answer. But I would not get excited about ripping the pump off immediately. If it sat for years as you say the seal was probably stuck to the housing. And when it was first turned over it broke loose and the two surfaces are not now sealed, or mated and are now seeping coolant. Clean the weep hole as best as you can and run the tractor for a period of time off and on for a few weeks there is a good chance the pump will re seat it self. A couple of days work in the field might do wonders. Always crack the oil pan plug before you start it in the morning and drain the water off.
MMDEL
 
Not what you want to hear but maybe a head gasket or crack somewhere. There is some tests for these issues.
 
Thanks for the replies. jocco that was his first thoughts but hes going to check and see if it might be the water pump he doesn't have a heated shop and right now its too darn cold
Thanks again GB in MN
 
If the tractor sits for a while, you can drain the engine oil out and remove the filter and the
steel canister it sits in (held in by two screws I believe) You can then look towards the upper left
corner of the engine which is where the water pump is located. If you see a small "trail" through
the oil stains in the crankcase it is coming from your water pump seal. That is what I did with my
M5 that I bought out of a grove. It is still running from several years ago yet. As MMDEL mentioned,
if it has been sitting it may seal up again. I would clean the weep hole by the water pump and give
it 1 or 2 shots of grease while running. Dont over grease it though.
 
An update on my brothers MM M602 he cleaned the weep hole in the water pump no coolant came so after running the engine more he decided to remove the heads and found nothing wrong with the head gaskets and could see no obvious cracks in the heads so he took them to an engine shop and after testing found nothing. So he figured there must be a crack in the block(s) he filled the blocks with coolant and it never went down in over a week so started to remove the blocks got the rod cap off the first rod went and turned the crack to get at #2 and some coolant ran down he figured it had to be the water pump and pulled it and the shaft was very worn got the water pump rebuilt so now its to reassemble the engine. The disassembly of the engine was not completely for nothing he did find a broke valve spring so that is repaired.
GB in MN
 

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