253 - knocking noise!

[dysolve]

hello all,
I have a 1982 V.H. wagon with a 253 and trimatic. It has always suffered from run on , well on a hot day. but yesterday instead of run on it had a knocking sound and I felt it in the brake peddle and the steering wheel. When I restarted the car I could hear nothing out of the norm. Today on the way home every time I slowed down or stoped I again could hear and feel the knock in the peddles and the wheel. I did not turn the car off and I quickly looked under the bonnet up the noise was gone and so was he peddle pulse. I checked all the fluids and everything seems normal. Done any one have any idea what's going on?
thanks!

[Paiste402]

could be a shagged engine mount so the engine is knocking onto the body at lower revs. Also check that its firing on all pots cause it may be a dud pot every now and again. Im just throwing ideas around here

[dysolve]

I started and drove the car this morning and everything seems fine. it still drives like it always has. thanks for the ideas already. I will get some plugs and leads tonight as it needs some anyway. engine mounts! now thats idea it will check them tonight also.

[TUF UTE]

check timing as for running on issues, and rip the old engine mounts out and put new ones in ...with a 355 attached

[dysolve]

check timing as for running on issues, and rip the old engine mounts out and put new ones in ...with a 355 attached

I suppose its cheaper to buy the engine mounts with the 355 attached then just the mounts :P

[Paiste402]

I suppose its cheaper to buy the engine mounts with the 355 attached then just the mounts :P

I agree, i think Supercheap auto is doing a special on Engine mounts where if you buy 2 sets and a crossmember they throw in a free 355 V8.

[dysolve]

I took the car for a drive tonight while it did not make the knocking noise when I stopped and turned the engine off and the radiator overflow filled up and hen water just poured out of the overflow tubes. What would the chances of a blocked cooling system?

[Jo3_Blo]

Woo, that sounds strange.

Maybe its the water pump..........but then it wouldn't fill up the overflow reservoir would it?
But then how would that cause you to feel it in the brake pedal??? Brake system isn't connected up to the cooling system in any way are they?
Could be something to do with vaccum if it is.

But meh, I don't really know what I'm talking about, so I'll stop confusing the situation. lol.

[SilverVH]

Run on is caused by timing (pre-ignition) Feeling a noise through a part of the car leads me to believe something in the drivetrain is amiss. Originally I thought maybe the exhaust is knocking on a body part at idle which could be a probable cause (exhaust pipe or exhaust manifold/extractor.) The other problem could be something like a rocker arm which is more unlikely as you shouldn't feel that through your steering wheel or brake pedal.

My guess would be the drivers side exhaust is hitting on the steering rack at idle due to engine vibration.

As for the overheating and running on, that is a totally different problem...

[dysolve]

the thing that makes me think they are related is that the knocking and the water overflow only happen after a "Fair drive" I drive about 10km to work each day and there is no problems. but I drove over 50 yesterday afternoon and thats when I noticed the water overflow issues but the knock did not happen.

[tigervh]

Sounds like preignition. This is often caused by a buildup of carbon in the combustion chamber glowing red hot and igniting the mixture before the spark plug gets a chance. You may need to pull the heads and scrape the crap off them.