Help!!!

[bowtie]

I have no water flow... I had a post a while back about a temp increase while pulling a tube, but it was concluded that it was do to the increased load. Well I decided to change my oil today and when I started the boat today I had no waterflow out the exhaust. This was with the lower unit submerged into a tank of water before and during the time the motor was running. I guess what I need to know is whether or not the water goes to the exhaust before the t/stat or afterwards. I suspect I either have a bad impeller or a bad T/stat, what do you think?

[bowtie]

I have no water flow... I had a post a while back about a temp increase while pulling a tube, but it was concluded that it was do to the increased load. Well I decided to change my oil today and when I started the boat today I had no waterflow out the exhaust. This was with the lower unit submerged into a tank of water before and during the time the motor was running. I guess what I need to know is whether or not the water goes to the exhaust before the t/stat or afterwards. I suspect I either have a bad impeller or a bad T/stat, what do you think?

[vinny p.]

Assuming that your engine is raw water cooled, the water flows from the sea water impeller ( if you have an alpha, its in the drive... bravo its on the side of the engine) through the engine, out the thermistat, out through the exhaust.

[vinny p.]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> I had a post a while back about a temp increase while pulling a tube, but it was concluded that it was do to the increased load. </div></BLOCKQUOTE>


This is no way no how true... By simply adding load, the engine should not get hot. If your impeller is good, I would bet the manifolds or risers are getting clogged up. That would cause a hot condition when under load.

[happy]

a quick check on the manifolds is to rig up a hose to the bottom fitting on your manifold and check for waterflow out the back.. (check your hose routing first) some engines are fresh water cooled.. and in some cases the manifolds are running coolant , and the risers are dumping raw water..

without seeing the engine.. i assume the cooling system is stock.. your by-pass will always flow water thru your manifolds..

[Eriktheviking]

One more thing to check is the water tube that goes between the bellhousing and the gimbal housing.Sometimes people use inferior hose or they install too long of a hose and it kinks closed when the drive is trimmed all the way down.I've also seen the case where the impeller broke apart and the pieces got stuck in the system and interrupted the flow of water.Is this is an Alpha or Alpha s/s?

[bowtie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Eriktheviking:
One more thing to check is the water tube that goes between the bellhousing and the gimbal housing.Sometimes people use inferior hose or they install too long of a hose and it kinks closed when the drive is trimmed all the way down.I've also seen the case where the impeller broke apart and the pieces got stuck in the system and interrupted the flow of water.Is this is an Alpha or Alpha s/s? </div></BLOCKQUOTE>
Alpha SS... I am guessing the impeller crapped out. I assume the coolings system is original, it is definately not a closed system. I am thinking the reason it would warm up when pulling a tube is because the impeller was not supplying enough water to keep it cool and since it was lugging the motor and generating quite a bit of heat yet was not moving fast enough for the water to be forced into the lower unit on its own. Whenever, I was running at speed, the temp never went over 160. I also noticed the last time out after dark when they have the minimum speed to plane rule that the temp gauge would fluctuate, steady around 160 but occasionally would rise to around 200, then drop back down to 160 and sometimes even drop lower. I wonder if it was because the impeller was bad and occasionally loosing prime and getting air in the system. About how long do these impellers usually last? I thought they were good for several years or about 200 hours, but this one is less than 2 years old and has less than 50 hours or so on it (the boat owner passed away and the boat put up for sale over a year ago). I have one last question, is there any site on the net with some maintenance instructions or "how to's" on typical procedures such as this. I have never worked on a lower unit before and would like a little guidance before I jump into it. Thanks

[vinny p.]

If you are not sure how to replace the impeller, just get the Merc service manual. Impellers and sleeves should be changed every year regardless of the number of hours.

[happy]

here goes the real deal... and this is how its done/quoted out for jobs... drive service.. pull the drive, change the impeller, and look at whats going on inside the transom assembly.. this includes checking your gimbal brg, shift cable, water inlet tube, gear lube bottle lube feed, and that lil thing called the engine coupler.. it needs grease too A(its either good or bad.. marginal doesn't count). bellows, and overall inspection of the gimbal ring.. and as the service manual says.. repair/replace as necessary.. next you go into the engine compartment.. i suggest the full meal deal 20hr svc.. every hose clamp... engine mounts, engine alingment. oil/filter change.. with notes on condition of fluids, engine mount bolts get checked to see if the lower nut has dropped.. manifold/risers are they leaking.. if this check is done right.. you will find the solution to the problem you have stubled across.. alot of work yes... but far less time behind a tow boat..

[Eriktheviking]

I'm 99% sure of what your problem is...If you look at your lower unit you'll see two rectangular plates held by four screws.The rectangle shaped o-rings that are behind those plates are bad and your sucking air and your loosing prime.They are NO longer available from Merc. What you have to do is clean up the area.Take black silicone and make a bead where the gasket goes and reinstall the plates.Let it dry and you'll be back in business.I'm willing to bet that your entire water pump assembly is bad.Once they get hot...its over.Let me know what you find.Good Luck

[bowtie]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Eriktheviking:
I'm 99% sure of what your problem is...If you look at your lower unit you'll see two rectangular plates held by four screws.The rectangle shaped o-rings that are behind those plates are bad and your sucking air and your loosing prime.They are NO longer available from Merc. What you have to do is clean up the area.Take black silicone and make a bead where the gasket goes and reinstall the plates.Let it dry and you'll be back in business.I'm willing to bet that your entire water pump assembly is bad.Once they get hot...its over.Let me know what you find.Good Luck </div></BLOCKQUOTE>
Thank you for the suggestion, I will check those ASAP. As it is I just had the impeller, housing, base, and everything else replaced as it was rather toasted. And again when I took it out, at low speed with the drive tucked all the way in the temp gauge was bouncing around. It would run 160 for a while, then drop to 0, then come back up to 170 or 180, drop back down to 160, then back to 0. I was beginning to think I either had a bad gauge or bad sending unit, but when I gave it a little more positive trim, the temp went right back to 160 and never dropped back to 0. This had me thinking that maybe with the drive tucked all the way in (down)where it is actually in a negative trim position it was disrupting the flow of water over the SS nose cone and since the water pick ups are just on top of the point on the nose cone that perhaps it was aerating the water flow over the cone and causing the pickup to suck air. And then of course this would cause an air pocket in thge cooling system that could not be measured causing the temp gauge to drop to 0. Of course if those gaskets are leaking, that would cause the same thing and possibly explain my impeller failure and my temp flunctuations as well.

[Eriktheviking]

You'll see as soon as you remove those plates.Whats happening is the water is being sucked in around those plates (occasionally).I had an S/S drive with the same problem.Just be careful removing those screws.Hopefully your new pump isn't toast....Doesn't take too long for that to happen.

[bowtie]

Well I pulled those plates off, and I can not say for certain whether or not either of them were leaking. One side appeared to have some white chalky debris around the seal, but it did not appear to cross the seal. For what it is worth, someone at one time or another had already pulled those of and added some sealant to them unless they used sealant from Mercruiser. By the way, I removed the old seals and they appear to be nothing but o-rings that had taken an oval set from being in there so long. I sized them up when I got to work and am planning on replazing them with a new set of o-rings. I will also add some silicone sealant just to make sure it is water tight as well. Thanks for the advice by the way, even if they were not leaking I am glad to know they could cause a problem and at least that will be one less item to worry about if the problem continues.