Hi everyone!
I am new here so tell me if I didn’t post at the right place or if you need other info.

I went for a long trip with my Ford 20 ft motorhome 1976 460cid and got issues. I always look for hours on the Internet and under my hood or go to see my mechanic, but this time I am far from home and I am kind of stuck.

• We have a loss of power that first happened while driving on a steep hill while the engine seemed to overheat. The gauge would not go further than just before mid-way/half which seems to be a normal range. But after I stopped, I could see some coolant sprayed out under the hood. It happened twice.

• Then it started to lose power after a 20mn drive and last time almost as soon as I went on the highway, but no overheating. - When the second overheating happened we also saw some engine oil sprayed out from the deep stick (quite a bit, enough to have to add some) and in the air filter (a few ml). After that, it happened every time the engine would need to work harder.

When we bought it, one month ago, there was some milky oil on the dipstick after one or two drives. I showed it to my mechanic (I was thinking about the head gasket) but he explained that it was condensation because the oil in the pan was clean and it was only on the dipstick. No loss of coolant, clean coolant and the engine was running really good.

Since all those issues happened, we changed the PCV valve and I think it did not change anything because I am pretty sure that a little bit of oil still gets out (I didn’t really get my engine working hard enough again for it to really spray out again as I have a loss of power too quickly. But when the engine is hot, I see some thin smoke coming out from the dipstick when I take it off).

Last night we checked the cylinder pressure (I was thinking about rings) and we got:

 

Oil blowby from the dipstick tube makes me tend to think it's the EGR plate hole is carbon fouled/plugged up. If you can squeeze the EGR valve (when it's runnin') and she dies, then (possibly) it'll be something different.

It seems like the crankcase isn't getting ventilated well enough and the pressure build up to where she's blowin' oil from any orifice.

Pull a coupla plugs.....what do they tell you?

And, welcome to FTE.

 

Thanks Filthy Beast! I will try that tomorrow.
Spark plugs were looking all the same when I pulled them out for the compression test: a little brownish/orange but nothing bad...

 

You have some type of restriction/malfunction in the Crankcase Ventilation System.

You need to either find a/or someone who has a 1976 OWNERS MANUAL to find the correct oil fill capacity. This can also be found in the SERVICE MANUAL.



A cylinder compression test will not give a blow-by indication, only cylinder compression.

Just an example-

Say the oil return holes in the cylinder head are plugged because of previous poor service, the PCV will not function correctly. The excessive crankcase pressure will push the dipstick out and force oil vapors to the ACL inlet vent.