Engine Rattle

[Guest richie rich]

Hello am new i have a mk4 cabby 1986 mfi since owning the vehicle i have noticed that when the engine is started from cold it is very qquite and sweet but when t gets warm it really rattles like mad the engine had been rebuilt before i had bought it and the engine was flushed threw i have put 10w 40 semi sythectic oil in is this ok as was thinking that maybe the oil gets to thin when the engine is hot and cause a lack of lube when hot has anyone come across this problem or any ideas what it might be lifters seem ok altho i cant press them in with my hands many thanks rich

[Guest Andy H]

hi ritchie

not got a great deal of knowledge about rattles and stuff but if its a top end rattle then you might wanna check the tappits if its a bottom end rattle maybe it could be the bottom crank shells have worn a little, failing that you could try changing the oil and put in 15/40 oil instead or try a reputable mechanic

[Paul Grainger]

You need to check the oil pressure cold and hot... I bet there will be a difference.

 

The rattle will be the valve lifters for sure, but the rely on oil pressure. If the crank bearings are worn the you will get the reduction in pressure.

 

Also quite common in these engines is the camshaft bearings causing exactly the same problem. If the oil pressure is down then remove the rocker cover and start the engine,(get a friend to start it so they can switch it off quick!) if the cam bearings are shot then you will see a gush of oil at the back of the head on the cam pully end (you will also need to protect the timing belt from oil contamination).

Good luck