Home |
Search |
Today's Posts |
#1
|
|||
|
|||
Mercruiser 470 Problems - can somebody help ?
Hi,
pls excuse my bad english because i`m from Hamburg, Germany. I bought an old Formula One equipped with Merc. 470 Engine. During test drive on an river with the owner engine start was fine, it went 41 knts for a while. Total test ride was about half an hour without problems or overheating. After transport to my home i did some test driving in salt water, but only short trips without problems. After that on my first longer trip i went 25 minutes with 22 knts at about 2300 rpm, stopped for two hours and then started to drive back. After 5 minutes at 2300 rpm engine sound changed, drove slower about 1500 rpm suddenly felt engine loosing power, then stopped at idle but engine shut off immediately. Temperature on instrument was not showing anything special but engine was extreme hot, smoking and melting the spark plug cables. After engine cool down i checked oil (was black and no sign of water) and water in internal circuit which was gone !!!. Checked impeller, was fine. At home equipped with new spark plug cables and plugs i filled up water and tried to start the engine whithout success. I checke again the manifold water reservoir and the water was gone again and there was a smell of gasonline. People told me i had to repair the cylinder head gasket because of the temperature destroying it. So i changed cyl head gasket, intake manifold gasket, exhaust manifold gasket and let the head be plained. The surface inside the combustion chamber was a bit rusty especially in cyl 1 and 3. After assembling filled up water and checked compression of cold engine which was about 6 bar on all cyls. I cranked the engine and it started working, shut off at idle rpm some times but then worked fine at idle rpm with flushing device. After engine running about 20 minutes checked water and a little bit was gone again. I decided to have a test drive after installing a new thermostat instrument (not the thermostat). On test drive went at about 2200 rpm for 15 minutes. Everything seemed fine, engine wasn`t running hot but shut off at idle rpm after stopping, was able to start engine again easily. Checked water in circuit, some water was gone, filled up much less than a quart (~ 1liter)again. After 15 minutes more at 2000-2500 rpm engine lost power, i stopped engine immediately. Checking oil now i found water in oil (grey), water in circuit was gone almost completely, reservoir smelled like exhaust smoke. I didn`t make an compression test untill today, cleaned the motor from oil/water mixture yesterday. I remember that the amount of oil was a little more than usual so somebody said that after the first drive with defects there could have been water in the oil which wasn`t emulgated and my mistake was not to change oil ? Do i have a cracked exhaust manifold / elbow ? I understand that this is the reason why the inner circuit is loosing water and old cyl head gasket was rusty. I don`t believe that i have a cracked cylinder wall because engine was running great during last test drive before the problems came again. But of course i don`t want to buy exhaust manifold/elbow without exactly knowing where the problem ist located. Does somebody have an idea or is there a possibility to test the exhaust manifold ? I know the preowner knows about the problem but doesn`t tell me ... best regards Olaf-Christian |
#2
|
|||
|
|||
Mercruiser 470 Problems - can somebody help ?
First go to www.breezeworks.net your motor is
about all they deal with. Your symptoms sound as if it is the exhaust elbow which is mounted on top of the manifold. It usually rots through and begins dumping the coolant into cylinder #4. If the top of that piston and the head at that cylinder were very clean when you took it apart then I am sure that is the problem. I have 2 of those engines, the starboard 1 just had that problem and actually broke the piston in half before I figured it out. Hope this helps. Terry "Olaf-C. Lepthien" wrote in message om... Hi, pls excuse my bad english because i`m from Hamburg, Germany. I bought an old Formula One equipped with Merc. 470 Engine. During test drive on an river with the owner engine start was fine, it went 41 knts for a while. Total test ride was about half an hour without problems or overheating. After transport to my home i did some test driving in salt water, but only short trips without problems. After that on my first longer trip i went 25 minutes with 22 knts at about 2300 rpm, stopped for two hours and then started to drive back. After 5 minutes at 2300 rpm engine sound changed, drove slower about 1500 rpm suddenly felt engine loosing power, then stopped at idle but engine shut off immediately. Temperature on instrument was not showing anything special but engine was extreme hot, smoking and melting the spark plug cables. After engine cool down i checked oil (was black and no sign of water) and water in internal circuit which was gone !!!. Checked impeller, was fine. At home equipped with new spark plug cables and plugs i filled up water and tried to start the engine whithout success. I checke again the manifold water reservoir and the water was gone again and there was a smell of gasonline. People told me i had to repair the cylinder head gasket because of the temperature destroying it. So i changed cyl head gasket, intake manifold gasket, exhaust manifold gasket and let the head be plained. The surface inside the combustion chamber was a bit rusty especially in cyl 1 and 3. After assembling filled up water and checked compression of cold engine which was about 6 bar on all cyls. I cranked the engine and it started working, shut off at idle rpm some times but then worked fine at idle rpm with flushing device. After engine running about 20 minutes checked water and a little bit was gone again. I decided to have a test drive after installing a new thermostat instrument (not the thermostat). On test drive went at about 2200 rpm for 15 minutes. Everything seemed fine, engine wasn`t running hot but shut off at idle rpm after stopping, was able to start engine again easily. Checked water in circuit, some water was gone, filled up much less than a quart (~ 1liter)again. After 15 minutes more at 2000-2500 rpm engine lost power, i stopped engine immediately. Checking oil now i found water in oil (grey), water in circuit was gone almost completely, reservoir smelled like exhaust smoke. I didn`t make an compression test untill today, cleaned the motor from oil/water mixture yesterday. I remember that the amount of oil was a little more than usual so somebody said that after the first drive with defects there could have been water in the oil which wasn`t emulgated and my mistake was not to change oil ? Do i have a cracked exhaust manifold / elbow ? I understand that this is the reason why the inner circuit is loosing water and old cyl head gasket was rusty. I don`t believe that i have a cracked cylinder wall because engine was running great during last test drive before the problems came again. But of course i don`t want to buy exhaust manifold/elbow without exactly knowing where the problem ist located. Does somebody have an idea or is there a possibility to test the exhaust manifold ? I know the preowner knows about the problem but doesn`t tell me ... best regards Olaf-Christian |
#3
|
|||
|
|||
Mercruiser 470 Problems - can somebody help ?
Hi,
You can pressure test the system with an automotive cooling system pressure tester. The exhaust elbow/reservoir, exhaust manifold, heat exchanger, and intake manifold can be tested for leaks by moving hoses around and or plugging them. Check the reservoir first because I suspect it has rotted thru to the exhaust cavity. Jim In MA "Olaf-C. Lepthien" wrote in message om... Hi, pls excuse my bad english because i`m from Hamburg, Germany. I bought an old Formula One equipped with Merc. 470 Engine. During test drive on an river with the owner engine start was fine, it went 41 knts for a while. Total test ride was about half an hour without problems or overheating. After transport to my home i did some test driving in salt water, but only short trips without problems. After that on my first longer trip i went 25 minutes with 22 knts at about 2300 rpm, stopped for two hours and then started to drive back. After 5 minutes at 2300 rpm engine sound changed, drove slower about 1500 rpm suddenly felt engine loosing power, then stopped at idle but engine shut off immediately. Temperature on instrument was not showing anything special but engine was extreme hot, smoking and melting the spark plug cables. After engine cool down i checked oil (was black and no sign of water) and water in internal circuit which was gone !!!. Checked impeller, was fine. At home equipped with new spark plug cables and plugs i filled up water and tried to start the engine whithout success. I checke again the manifold water reservoir and the water was gone again and there was a smell of gasonline. People told me i had to repair the cylinder head gasket because of the temperature destroying it. So i changed cyl head gasket, intake manifold gasket, exhaust manifold gasket and let the head be plained. The surface inside the combustion chamber was a bit rusty especially in cyl 1 and 3. After assembling filled up water and checked compression of cold engine which was about 6 bar on all cyls. I cranked the engine and it started working, shut off at idle rpm some times but then worked fine at idle rpm with flushing device. After engine running about 20 minutes checked water and a little bit was gone again. I decided to have a test drive after installing a new thermostat instrument (not the thermostat). On test drive went at about 2200 rpm for 15 minutes. Everything seemed fine, engine wasn`t running hot but shut off at idle rpm after stopping, was able to start engine again easily. Checked water in circuit, some water was gone, filled up much less than a quart (~ 1liter)again. After 15 minutes more at 2000-2500 rpm engine lost power, i stopped engine immediately. Checking oil now i found water in oil (grey), water in circuit was gone almost completely, reservoir smelled like exhaust smoke. I didn`t make an compression test untill today, cleaned the motor from oil/water mixture yesterday. I remember that the amount of oil was a little more than usual so somebody said that after the first drive with defects there could have been water in the oil which wasn`t emulgated and my mistake was not to change oil ? Do i have a cracked exhaust manifold / elbow ? I understand that this is the reason why the inner circuit is loosing water and old cyl head gasket was rusty. I don`t believe that i have a cracked cylinder wall because engine was running great during last test drive before the problems came again. But of course i don`t want to buy exhaust manifold/elbow without exactly knowing where the problem ist located. Does somebody have an idea or is there a possibility to test the exhaust manifold ? I know the preowner knows about the problem but doesn`t tell me ... best regards Olaf-Christian |
#4
|
|||
|
|||
Mercruiser 470 Problems - can somebody help ?
|
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Mercruiser 120 and Delco EST igntion | General | |||
? Mercruiser oil vs synethic oil | General | |||
Mercruiser 120 engine problems | General | |||
Motor Problems (Please help) | General | |||
Need help Properller size Mercruiser Alpha One | General |