Head gasket and what else?

[Brckridnbob]

I have a 95 K75. Last week stopped at ferry dock and was idling. Fan came on, then the fan went off. Short time later engine begin to cough, sputter, and idle very roughly. I was able to ride home, but major drop in power.

I checked it out and have coolant in the oil, coolant overflow is empty, and radiator level dropped below viewable area. So, I'm pretty sure its got a blown head gasket. In the drained oil I found thin carbonized metallic material (cracked valve?) and also pieces like in the attached picture.

It looks like plastic, is transparent, and flexible. What is this thing - piece of a valve guide?
For those who have experienced such things did you end up having other damage inside upon further inspection?
Think its ridable to the mechanic without risking additional damage (~12 miles)?

Thanks for your input!!
Bob

[lostboy]

I wouldn't ride it anywhere. This does sound like a blown head gasket, and at this point, simply replacing the gasket may fix it. Running the bike could result in damaged gasket surfaces.

I don't recognise the piece you show. Can you give us an idea of it's size?

[58058D]

Would agree with that....don't run the engine any more until it is fixed.

[deilenberger]

I'd suggest you start looking for another engine. It's rarely economic to repair a K75 engine.. the parts alone cost more than a used engine (they have little value on the used market since they so rarely fail.) The only reason to take the old one apart is curiousity IMHO.

Going price lately seems to be around $350-400 for a good known mileage used engine.

YMMV but I doubt it.

[Brckridnbob]

The piece of plastic is about 4 mm wide x 5 mm high. Its transparent and is flexible but stiff. Looks like it may have been colorless at one point but now is an oil-stained yellow-brown color.

I talked to the mechanic and he said in addition to the head gasket there is a high likelihood it will need a valve job/head rebuild (I trust this guy and he's got a great reputation as a straight shooter).

So, looking at cost of parts, getting a replacement engine makes a lot of sense. For comparison, this ones got 50K on it. The dilemma is whether I buy a used engine and find out its got its own set of problems? Maybe the chances of that are low considering the (usually) bulletproof nature of K motors? just wondering if its trading the devil I know for one that I dont.

Good thing I have another K to rid in the meantime ;)

Bob

[deilenberger]

The piece of plastic is about 4 mm wide x 5 mm high. Its transparent and is flexible but stiff. Looks like it may have been colorless at one point but now is an oil-stained yellow-brown color.

I talked to the mechanic and he said in addition to the head gasket there is a high likelihood it will need a valve job/head rebuild (I trust this guy and he's got a great reputation as a straight shooter).

So, looking at cost of parts, getting a replacement engine makes a lot of sense. For comparison, this ones got 50K on it. The dilemma is whether I buy a used engine and find out its got its own set of problems? Maybe the chances of that are low considering the (usually) bulletproof nature of K motors? just wondering if its trading the devil I know for one that I dont.

Good thing I have another K to rid in the meantime ;)

BobFWIW - I've never seen a K engine that needed a "valve job" or "head rebuild".. perhaps your mechanic is basing that on the engine overheating, in which case, the head may well be warped. Paul Glaves K75 had 350,000 miles on it when taken out by a minivan - and the engine had never been opened. These are one really tough engine if they don't overheat.

The chance of a new engine having problems is always a worry - but with even minimal care, the chance IMHO is very low. Most sellers offer a money-back deal (at least used parts dealers).

Call around - see what's in stock and what sounds good. An engine without ancillaries (starter, alternator, injectors, intake TBs) is usually considerably cheaper than a fully built engine, and since you know those parts are OK from your engine, no reason I can think of to not reuse them.

[98lee]

http://cgi.ebay.com/ebaymotors/1991-BMW-K75-ENGINE-MOTOR-3-CYLINDER_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q 3a2Q7c39Q3a1Q7c72Q3a1205Q7c240Q3a1318Q7c301Q3a1Q7c 293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhash Zitem3352b6fd3fQQitemZ220431056191QQptZMotorcycles Q5fPartsQ5fAccessories#ht_500wt_1002


:dance:dance:dance

[Brckridnbob]

Thanks for the tip, looks promising! Shipping calculator came in at $300 - even at that probably still worth bidding.

[Librarian]

Look for someone local. I know there are some people over in Seattle who sell used K-bike stuff: http://www.kbikeparts.com/

[chuck_donahue]

I had the same thing happen. It was not the head gasket, it was the seal between the oil/water pump. Alot easer fix, but it cost more.

Chuck

[98lee]

I had the same thing happen. It was not the head gasket, it was the seal between the oil/water pump. Alot easer fix, but it cost more.

Chuck

Did you end up with coolant in the oil?


:dance:dance:dance

[Brckridnbob]

I had the same thing happen. It was not the head gasket, it was the seal between the oil/water pump. Alot easer fix, but it cost more.

Chuck

Was there any particular factor/symptom that led to the oil/water pump?

[chuck_donahue]

The oil and coolant are only seperated by a rubber seal. Mine was 20 + years old. And yes I had coolant in my oil. That is my bet. Pull it out and look at it. What do you have to loose. New pump about 400+.
Come to think of it, I still have that pump ... I think. I will look and take a couple pic's if it would help. But I think If you ran it very long, change the motor.

Chuck

[JamesBayles]

Water pump seal leak should leak out of "weep" hole, not mix w/engine oil. The over temp light should have come on before any damage was done. CHECK OPERATION OF LIGHT, before riding, after repair. There are numerous tests to determine if combution gas is leaking into cooling system, ("blown" head gasket).
If in fact head gasket no longer seals properly, it is due to the cylinder head casting being distorted by overheat. Replacing a head gasket, on any engine, has NEVER! remedied any sealing problems. You do need to determine the original cause of overheating, (lack of cooling fan, maybe the sound you heard was its last sound?) lack of coolant (leak), lack of circulation (pump/thermostat/radiator) Good luck and keep us posted!

[Brckridnbob]

Mechanic cant get to it for a bit so I checked the compression. 125psi dead even for all 3 cylinders. Still within BMW service limits!

Buoyed by this and Chucks tip I pulled the oil/H20 pump. Sure enough the seal is toast and the housing is badly pitted. Oil weep hole was plugged with debris.

So good engine, bad pump, much $, straightforward fix.

LONG LIVE THE BRICK!

:bikes :thumb

[98lee]

Lets hope the coolant in the oil did not trash the rod and main bearings.


:dance:dance:dance

[chuck_donahue]

A rebuild kit is about $80 I think. But I bet yours is as bad as mine and chewed up where the seal goes (not rebuildable). A new one is about $400. I think If you could get the whole motor with a good pump in it for less than 400, spend the $80 and rebuild the pump from the new motor. then If your motor dies, you have a spare.

[deilenberger]

The oil and coolant are only seperated by a rubber seal. Mine was 20 + years old. And yes I had coolant in my oil. That is my bet. Pull it out and look at it. What do you have to loose. New pump about 400+.
Come to think of it, I still have that pump ... I think. I will look and take a couple pic's if it would help. But I think If you ran it very long, change the motor.

ChuckActually - they are separated by a rubber seal, an air-gap and a mechanical carbon seal. The mix can only happen IF the weep hole for the air-gap is solidly plugged up. I've heard of this happening only a very few times in many years.

That said - if any antifreeze got into the oil - chances are excellent some bearing damage has likely occurred. Given the work involved rebuilding a K engine, and the parts cost - a good used engine is a bargain.

[Brckridnbob]

I finally got around to doing the pump replacement. I approached it with optomism as neither the red (oil) or yellow (overtemp) light had come on at the beginning of this whole incident (I would have stopped riding the bike right there if they had), AND since the compression test was good.

Outcome - bike runs great! Probably better than before, seems more responsive! :dance

Sure, I may still have a bearing go in the not to distant future ending in a trashed engine but so far everything is a-ok! Chock another vote up for checking the oil/water pump intermediate seals if you encounter a situation similar to mine.

Thanks all for your thoughts and advice!!! :thumb