umpire111

Ok, tested mounts again by putting large screwdriver underneath each and lifting, also checked bottom nuts, seem ok. Also no deposits around rubber mounts. Not sure where air intake is

Will check the mounts again and come back, there isn't an air filter.

Sorry, should have said that I have checked that and all ok.

Isuzu 35 engine has been firing well for years, runs smoothly at all revs. Just recently at cruising speed, 1000 revs the engine soundis as though it's judering, t does not do this at 800 or 1200 revs. I filled with fuel about 30 hours engine time before the judder started. Have checked engine mounts and they seem fine. Filters changed about a month ago. When I run engine out of gear the judder is far less pronounced, no air filter in this type of engine...any ideas?

Tony, many thanks for the well constructed and knowledgeable advice. Thought would update you, put in two isolation valves, when either or both turned off, problem still existed. Shelled out fior a new pump today.......problem solved. So both of the pumps I used have same problem. Rang Whale and they suspect it's a problem with the internal micro switches. Thanks for your time, appreciated. Have spent hours trying to sort this.

Have just come to top up the header tank for my radiators. Bit concerned as the stuff I keep is blue, ready mixed and says on it, "silicate", I know that different types of anti freeze should not be mixed. The stuff in my header tank is red but the bottled stuff I have is very blue! Any ideas what type is in my radiator system or how do I check?

Thanks but passed that already, heading for Hatton flight now. Do you think this could be connected, found the crud while exploring ump issues.

Same OP, could there be a connection between crud and recycling pump?

Gunge out of calorifier- there is a drain pipe coming out the bottom of the calorifier. Opened it tonight into a bowl and out came brownish tint water with lots of black bits, is that normal or do I need to give it a good drain and clean.

Gunge out of calorifier- there is a drain pipe coming out the bottom of the calorifier. Opened it tonight into a bowl and out came brownish tint water with lots of black bits, is that normal or do I need to give it a good drain and clean.

None in Warwick

Thanks, in Warwick now so hope I can find a plumbing merchant. Watch this space

Sounds sensible idea. On the outlet side of the pump it soon splits into two, what I will do is to insert a valve so I can totally isolate the output. Or would you put in two valves, after the split? Could send a photo but can't seem to upload it. Thanks for all advice. I don't have an accumulator.

Central heating has its own header rank and engine def separate system. No gas heater and as far as internal calorifier leak goes, I am lost there, how can I tell?

Both the engine cooling and central heating are independent systems and not connected to problem pump. Bilges are absolutely dry. Thanks again.

I isolated the toilet bya valve in the inlet pipe at the back of the loo and same problem, so I assume it's not toilet. Also it's a new PRV and I placed tissue paper in the external outlet and it's bone dry......frustrating or what?

Not a new pump but a spare, coincidence if both had same problem

Sorry, on Gt. Union and reception a bit iffy. Ok, turned the tap from the tank to the pump off when all up to pressure as still problem exists. Pump still cycles on. Perhaps you could help as not sure what that tells me. Thanks for help

Determined to find the problem/leak etc.

Will try that, thanks

Thanks, don't have an accumulator, determined to find it,

As I type am turning off isolation valves, only found two, one for loo and other calorifier, turned both off me at a time and problem continues!

Tried another pump and same problem.

Checked pro, outlet dry, put tissue paper in to check. No leaks anywhere and all bilges dry. It's been going on about a month now.

All bilges are dry, checked all pipe work thoroughly