Run engine for twenty minutes and cuts out ..very hot block ...Cant touch dipstick, too hot..inlet manifolds very hot...
What could cause this seriuos over heating...dont wont to sieze it up...please help...
Regards
Al
Engine Overheating !!! SORTED
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Aircooler80
- Posts: 7
- Joined: 26th June 2006 - 7:28pm
- Location: Shropshire
Engine Overheating !!! SORTED
Hi everyone I'm a newbie on here and wonder if any of you can help me..Please...I have a 1795 T4 engine which is overheating..full tinware in good condition, engine bay sealed, flaps open with full flow of air over cylinders..Plenty of oil in engine, middle point on dipstick.
Run engine for twenty minutes and cuts out ..very hot block ...Cant touch dipstick, too hot..inlet manifolds very hot...
What could cause this seriuos over heating...dont wont to sieze it up...please help...
Regards
Al
Run engine for twenty minutes and cuts out ..very hot block ...Cant touch dipstick, too hot..inlet manifolds very hot...
What could cause this seriuos over heating...dont wont to sieze it up...please help...
Regards
Al
Last edited by Aircooler80 on 6th July 2006 - 5:53am, edited 1 time in total.
1795 Aircooler Type 4
Engine overheats
Sounds as if you've the cooling air flowing - getting a good blast of air out? Has the cooler been out? Cleaned of muck blocking the fins? Oil pressure OK? Is the vehicle moving (brakes free?) or just running the engine at standstill?
Oil relief valve opening and closing? At start-up the oil doesn't go through the cooler - maybe the plunger is stuck and isn't allowing it to get to the cooler when warmed up.
Maybe ignition timing is out - that can make things run hotter, but whether that much hotter I'm not sure. Remember the Type 4 ignition is timed at a lot of RPM for a certain amount of advance. 3.500 vac hoses off timed at 27 deg BTDC for FI and 32 deg BTDC for twin carb it says in Haynes. you need to have a mark on the fan pulley to show where this is - either a degree plate on the pulley or work it out from 360 degrees all the way round.
I'm assuming you have a Type 4 411/412 - or is it in a camper?
Oil relief valve opening and closing? At start-up the oil doesn't go through the cooler - maybe the plunger is stuck and isn't allowing it to get to the cooler when warmed up.
Maybe ignition timing is out - that can make things run hotter, but whether that much hotter I'm not sure. Remember the Type 4 ignition is timed at a lot of RPM for a certain amount of advance. 3.500 vac hoses off timed at 27 deg BTDC for FI and 32 deg BTDC for twin carb it says in Haynes. you need to have a mark on the fan pulley to show where this is - either a degree plate on the pulley or work it out from 360 degrees all the way round.
I'm assuming you have a Type 4 411/412 - or is it in a camper?
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Aircooler80
- Posts: 7
- Joined: 26th June 2006 - 7:28pm
- Location: Shropshire
Hi thanks for reply..
First bit of history.
Obtained engine from military, its a NOS (new old stock) 1795cc complete with everything, including carbs and exhaust; only needed mounting bar,flywheel and clutch. Fitted it in my camper in last few weeks.. Answers to your questions:
getting a good blast of air out? Yes
Has the cooler been out? No its new alraedy fitted to engine when received
Cleaned of muck blocking the fins? None evident
Oil pressure OK? Yes
Is the vehicle moving (brakes free?) or just running the engine at standstill? standstill now but does same when driven
Oil relief valve opening and closing? Dont know this .How do I check?
Timing checked and spot on
I'm assuming you have a Type 4 411/412 - or is it in a camper? Engine is in a camper
Al
First bit of history.
Obtained engine from military, its a NOS (new old stock) 1795cc complete with everything, including carbs and exhaust; only needed mounting bar,flywheel and clutch. Fitted it in my camper in last few weeks.. Answers to your questions:
getting a good blast of air out? Yes
Has the cooler been out? No its new alraedy fitted to engine when received
Cleaned of muck blocking the fins? None evident
Oil pressure OK? Yes
Is the vehicle moving (brakes free?) or just running the engine at standstill? standstill now but does same when driven
Oil relief valve opening and closing? Dont know this .How do I check?
Timing checked and spot on
I'm assuming you have a Type 4 411/412 - or is it in a camper? Engine is in a camper
Al
1795 Aircooler Type 4
Overheating Type 4 engine
If it's a new engine, it might get hot in the initial stages, as it is tighter at first, but it shouldn't get hot enough to stop, even on our hottest day.
What oil have you put in? Did you change what was in there first? It may have been filled with inhibitor if in store - it's not a lubricant.
Any sign to suggest it's a very weak mixture - plug colour, tail-pipe outlet sooty or grey/white?
Does the thermostat expand as it gets hot? Might be faulty, not allowing the air to flow over the cylinders properly. There are flaps in the cooling system that start closed to allow the engine to warm up quickly, but get opened by the expanding thermostat.
I think you said the flaps were working though.
Under the sump near the back there is a big pan-head screw with spring and plunger above. This is the oil pressure relief valve, and gets pushed open by higher than normal oil pressure when cold, allowing it to by-pass the oil cooler and go straight to the bearings. When warm, the spring moves it back to its running position.
You would have to drain the oil I think, undo the screw and catch the spring and piston. If the piston won't fall out, it may have a tapping in the lower face to screw something in - M6 thread maybe - and pull out. Maybe it's gummed up.
There's an oil pressure control valve on the top right front area of the case, towards the fuel pump I guess. I don't know if this can cause a similar problem.
I'm racking my brain now - can't think of any other reason. Give Jane and Brian Terry in Kent a ring 01303840241.
What oil have you put in? Did you change what was in there first? It may have been filled with inhibitor if in store - it's not a lubricant.
Any sign to suggest it's a very weak mixture - plug colour, tail-pipe outlet sooty or grey/white?
Does the thermostat expand as it gets hot? Might be faulty, not allowing the air to flow over the cylinders properly. There are flaps in the cooling system that start closed to allow the engine to warm up quickly, but get opened by the expanding thermostat.
I think you said the flaps were working though.
Under the sump near the back there is a big pan-head screw with spring and plunger above. This is the oil pressure relief valve, and gets pushed open by higher than normal oil pressure when cold, allowing it to by-pass the oil cooler and go straight to the bearings. When warm, the spring moves it back to its running position.
You would have to drain the oil I think, undo the screw and catch the spring and piston. If the piston won't fall out, it may have a tapping in the lower face to screw something in - M6 thread maybe - and pull out. Maybe it's gummed up.
There's an oil pressure control valve on the top right front area of the case, towards the fuel pump I guess. I don't know if this can cause a similar problem.
I'm racking my brain now - can't think of any other reason. Give Jane and Brian Terry in Kent a ring 01303840241.
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Aircooler80
- Posts: 7
- Joined: 26th June 2006 - 7:28pm
- Location: Shropshire
HI and thanks again for reply.
I drained and filled with 20/50, put new filter on.
I have new solex 36-40 on that dont have the central idling syetem that im used to on. I assumed the mixture screw on esch carb is at the back at the bottom next to join with manifold..set at 2 turns out each? throttle basic setting 0.1 mm feeler gauge?
I'll drain the oil and check the valve out ..
Thanks again
Al
I drained and filled with 20/50, put new filter on.
I have new solex 36-40 on that dont have the central idling syetem that im used to on. I assumed the mixture screw on esch carb is at the back at the bottom next to join with manifold..set at 2 turns out each? throttle basic setting 0.1 mm feeler gauge?
I'll drain the oil and check the valve out ..
Thanks again
Al
1795 Aircooler Type 4
Overheating
I personally don't like 20-50; it's heavier than it needs to be and the flow through the oil-cooler is reduced. Many people run on Morris 30 grade, but many others put almost anything else in too, so I don't think that's the real problem - but it might be the final straw.
Maybe your carb isn't adjusted right yet. A CO meter is the best way to adjust the mixture really. Somewhere around 3% usually is good for an aircooled carb.
General technique is to turn the mixture screw out until engine revs start to drop then turn in gradually, noting the revs increase, then start reducing again. Unscrew a bit from that to leave it a bit on the richer side. Adjust the bypass screw (big one) for about 850 - 900 rpm.
Two carbs need balancing, but you can do the mixture on each separately if the (idling) airflow is reasonably balanced - just not quite so obvious as with a single.
Worth checking a plug from each head to see if there's a problem with one carb running particularly weak. Maybe there are a few causes adding up, but nothing catastrophic. Hope so.
Maybe your carb isn't adjusted right yet. A CO meter is the best way to adjust the mixture really. Somewhere around 3% usually is good for an aircooled carb.
General technique is to turn the mixture screw out until engine revs start to drop then turn in gradually, noting the revs increase, then start reducing again. Unscrew a bit from that to leave it a bit on the richer side. Adjust the bypass screw (big one) for about 850 - 900 rpm.
Two carbs need balancing, but you can do the mixture on each separately if the (idling) airflow is reasonably balanced - just not quite so obvious as with a single.
Worth checking a plug from each head to see if there's a problem with one carb running particularly weak. Maybe there are a few causes adding up, but nothing catastrophic. Hope so.
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Aircooler80
- Posts: 7
- Joined: 26th June 2006 - 7:28pm
- Location: Shropshire
Hi again
I have it sorted..When I got the engine I assumed as it was unused and NOS all unternal factory settings would have been set ready to run. I was wrong..... All valve clearances were set at NO clearance plus 1/2 a turn, similar to engine with hydros.But this engine has solids! So the van was starting and warming up, then cutting out due to valves not closing properly when hot.
So set clearances correctly and the engine runs graet now..
Thanks for your help
Nice feeling
Al
I have it sorted..When I got the engine I assumed as it was unused and NOS all unternal factory settings would have been set ready to run. I was wrong..... All valve clearances were set at NO clearance plus 1/2 a turn, similar to engine with hydros.But this engine has solids! So the van was starting and warming up, then cutting out due to valves not closing properly when hot.
So set clearances correctly and the engine runs graet now..
Thanks for your help
Nice feeling Al
1795 Aircooler Type 4