Do you let your TV warm up before towing?

Turtle n Peeps wrote:

Wes Tausend wrote:

I agree nearly 100% in this long earlier post.

I know the scored cam can occur particularily in overhead-cam engines (OHC) (usually gas) because of delayed oiling from slow, thick oil. Note Ford swapping to 5W20 from 5W30 on their early OHC engines.

I don't understand the bent pushrod reference in OHV engines though. Do any of you know what the root cause regarding cold engines/bent pushrods might be? Or is it possibly a rare to non-existent issue here? I do understand that bent pushrods can occur with an engine that has been stored unlubed for a long time... due to corroded stuck valves. Or bent connecting rods due to hydraulic lock from a coolant leak (cavitation or headgasket).

Wes
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Stop it. :S

Come on, when is the last time you heard of a cam failure? Roller cams need next to no oil. We restrict the passages down to almost nothing and they still live just fine. Even non roller cams are really good now days and I don't even hear of any failures.

Turtle,

You are quite correct that OHC failure is fairly rare, but not unheard of. Ford Triton engines are susceptable.

Here is a paragraph and link similar to logical information I have read earlier on OHC failure:

Fourth paragraph from the top, quote:
Lubrication is another issue with OHC engines. Most late-model engines are factory-filled with lightweight 5W-20 or 5W-30 oil, and with good reason. Thinner oil reduces friction and improves fuel economy. It also improves cold start lubrication. The OEMs typically recommend 5W-20, 5W-30 or even 0W-20 for OHC engines because the oil remains thin enough during cold weather to reach the camshaft in a reasonable amount of time following a cold start. Thicker oils such as 10W-30 and 10W-40 take longer to reach the upper valvetrain after a cold start - and may increase the risk of cam damage when temperatures plunge below freezing.


My first personal experience was a buddy with a late 70's Yamaha TT500 single cyl/OHC motorcycle that he used in a dragrace challenge with snowmobiles during a frigid ND winter day. He left the summer oil in it and consequently burned up his overhead cam.

I am interested in reference to the possibility that dry OH valves might stick in cold weather, and account for a bent pushrod, as someone mentioned. I don't think they will, so I don't understand how bent pushrods are a consequence of cold starts in OHV engines. Do you know any different?

Thanks,
Wes
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