Inliners International Forums General Discussion Engines Any ideas on this one? 250, all lifters tapping

I took my other stock 1975 250 into the shop the other day. Here's the scoop on it. It was running perfect, then ALL the rockers started tapping like crazy all of a sudden when I was driving home one day. All of them, not one or a couple. I pulled off the road, tried to adjust the timing and then the rockers in the parking lot, but nothing doing. I drove it home and it ran perfect, no missing, perfect idle at stop lights, good power, good oil pressure, good temp, everything was perfect except it was tapping like the oil pump was gone or I ran it out of oil or something. Yes, it had oil and a fresh filter too. Again, it ran perfect still and all the guages were normal. I came across a deal on a new engine from a friend so I didn't mess with it, and I a yanked it and it has been sitting ever since.

Fast forward a year and now I am toying with it and I took it to my engine rebuilder who says that a commin problem is that the cam gear gets messed up and the cam slides out of position a little and the lifters dont seat directly on the cam lobes. Usually all that is needed is a new cam and gear set. BUT he called me today saying the cam looks perfect. He cannot find anything wrong with it. he said there are no metal flakes but he did find TWO gear teeth that look like they are from the distributor in the oil pan. Who knows when they could have gotten there. the engine still ran good and when I got a new engine I pulled the distributor out and out it in the new engine, so it simply cannot be the distributor as he is thinking it is.

So taking what has said, and also ignoring what he has said, any ideas? The oil filter was a FRAM could it have collapsed and still read good oil pressure? That is the oly thing I can think of.

what are you calling good oil pressure? is this at idle or off idle?(meaning driving RPMs?) Have you checked or looked at the
rocker studs? IF ??? The filter did collaps The block has a built-in bypass.So yes you still would have had oil pressure But you would have also put any trash that may??? have been in the filter through the motor.

How does the bearings look? Did the oil smell of gas? Check the lifter oil passages for a blockage that would prevent oil flow to lifters.
My brother-inlaw several years ago had a fuel pump start leaking into the oil causing extreme dillution he swore that the oil light never came on but his lifters were hammering bad. Needed a complete rebuild, but knowing him he drove it that way for a week before he said anything.

As far as oil presure there are no numbers, but it was at 3/4 up when driving and 3/8 at idle. That is the norm for all the other engines I had in the truck so I felt that was ok.

I don't remember if I looked at the rocker studs personally, but I am sure the mechanic did, but I can ask to be sure. I thought about that but all of the studs backing off right at the same time seemed unlikely. When it started it just came on all at once.

He said the bearings looked good and there was no metal in the pan either except for the two teeth. that could have been from an old distributor that was replaced 10 years before though who can say.

I will tell him to be sure and check the oil passages, studs and fuel pump to be sure.

Fuel Smell in Gas: Yes it is a real thing. I had a Buick that would do that. On hot days the idiot light would come on at idle. In the Navy I worked on Big Diesels and it was a standard thing to check for... "Fuel Dilution" That is the fancy word for Fuel in the Oil.

So do an Oil Change. If it is an old motor use 40W or 50W. I aint gonna go into 10W-40 or all that. Just use a thicker oil and see if that quitens your lifters.

In closing, one signature sound of an inline 6 is a mild click of the lifters. To wit: They sound like a sewing machine. So change your oil then call us back.

Low on oil.

MBHD

I checked the oil as soon as I pulled off the freeway the day this happened, it was normal and I did not smell anything foul. It was Castrol 10w 40 and it was a fresh oil change with only a few hundred miles on it.

Talked to the mechanic today and he pulled the cam and didn't find anything wrong, I asked him about the oil smell and he said there was no gas smell at all.

I have owned a number of inline 6's and am familiar with their sound. This is different, as I mentioned it was running and sounding normal when the sound suddenly changed. I am going to pick up the engine pieces and mess with it at home now. Probably just put the head off of it, on the block that is in my truck now since I don't want the 292 head that is on there.

The engine is torn apart so I can't exactly change the oil and crank it up, but I plan on getting/building a run stand since I have another 250 sitting in my garage (yes a third one). Here is a utube video I took of it when this happened...

http://www.youtube.com/watch?v=hwCT9iNM4lw

Maybe the relief valve in the oil pump got stuck for a bit then returned to normal or it stayed that way?
No oil pressure gauge huh?
Oil pickup plugged?

MBHD

It's a 71 chevy truck. It has the factory guage with increments, just no numbers. Gauge works properly though, I drive the truck now with a different engine in it. I am not sure at this point I mean, running the engine without the valve cover, I could physically see oil pumping up and draining down. Blowin my mind. When I get it home this weekend I am seriously going to check the oil passages for trash though.