"Check Engine light" flashes when going down a steep hill

[Phil V]

I'm afraid you might be right Cruiser... But I've been thinking that for years now...

I have foam under the oil filler cap, and it's been like that for years, but the oil on the dipstick looks fine.

A lot of people say that the foam on the filler cap is normal... "It's just condensation", and stuff like that.

But when I look at that pic of the plugs in the post above, the color makes me think there might be something going on there between the #2 and #3 cylinders. They're right next to each other..

I'll have to check with the local parts stores about that test kit, I wonder what I'll find in the radiator...

Jim, if you think it might be a faulty head gasket then do a cylinder leak down test. Or you could use an adapter that screws into the spark plug hole and the other end of the adapter to an air hose. Plug the thing into the air hose with at least 90psi and take your radiator cap off. if the head gasket is bad then you will see air bubbling through the anti freeze in the radiator.

You can get a regular cylinder leak down test kit from Horrible Freight pretty cheap. https://www.harborfreight.com/cylind...ter-62595.html I bought one of those kits and it works like it's supposed to.

[Jim2]

Thanks for the suggestions you guys.. It looks like the leak down testing kit and the "Block tester" cost about the same.

But my truck doesn't have a radiator cap, so I wonder how those tests would work at the overflow tank?

[07cruiser]

Good question, I'm not sure. So what I would do is like Phil V said is to do a leak down test. You'll either see bubbles in the overflow or you'll hear it coming out of the exhaust or even the intake.

[roadiestar]

One way to check for head gasket leak .Is to take the cap off the rad start engine let run to its warmed up. Once warm look in the rad and see if there is any air bubbles coming up. If you see any you have a bad head gasket.

[Henry]

One way to check for head gasket leak .Is to take the cap off the rad start engine let run to its warmed up. Once warm look in the rad and see if there is any air bubbles coming up. If you see any you have a bad head gasket.

Not necessarily! Most times the bubbles are an indication that 'air' was introduced into the system. Leaving the cap off is one way of 'bleeding' the air out. Other ways are bleeders on the block or head(s) on vehicles with them.

Henry

[Ronf]

Thanks Bob

It's a 2WD, automatic... I think the u-joints are pretty good, no noises or clunks, but I haven't checked it close in a while.

What you said about the valves earlier though, that one has me curious.

When I did the compression test, #2 was the low one @139. When I put a little oil in there, it only came up to 150. The highest readings on the others were up around 175-180. So yeah. I think it has something to do with the valves.




I did check the oil when it first happened. It was about half quart low, so I topped it off. But the same thing happened again next time I came down that hill.

And yeah, it's not fully warmed up when I come down that hill. It a house where I was working at, so the engine is cool when I'm heading down in the afternoon.

It seems strange that the light doesn't flash on the way up though... A few years ago, I had the flashing light and it was really bad. The pinging was loud and there was no power. The codes showed 2 or 3 cylinders misfiring back then. I replaced the coil pack, plugs, and wires, and that fixed it right up.

Thanks again Bob

Compression test for all cylinders should be with 10% of each other. I suspect you either have a bad valve guide or seal on #2 cylinder. Your plug tells me bad valve seal, especially since you did the ring test.

[Ronf]

Jim, if you think it might be a faulty head gasket then do a cylinder leak down test. Or you could use an adapter that screws into the spark plug hole and the other end of the adapter to an air hose. Plug the thing into the air hose with at least 90psi and take your radiator cap off. if the head gasket is bad then you will see air bubbling through the anti freeze in the radiator.

You can get a regular cylinder leak down test kit from Horrible Freight pretty cheap. https://www.harborfreight.com/cylind...ter-62595.html I bought one of those kits and it works like it's supposed to.

Phil gives you great advice. I make these pressure testers for this exact scenario when I am searching for a blown head gasket. You simply knock the ceramic off the plug, cut it at base and tap it for a serrated valve. Pressurize cylinder, pull rad cap and look for bubbles. This tool can also help in looking for bad valve seals and guides.

[Ronf]

After reexamining your post I think you have a blown head gasket in number 2 cylinder that is bleeding over (partial bleed through) to #3.

[Jim2]

Compression test for all cylinders should be with 10% of each other. I suspect you either have a bad valve guide or seal on #2 cylinder. Your plug tells me bad valve seal, especially since you did the ring test.

Thanks Ron, especially for your comment on the #2 plug. If you could expand on that, I'd like to understand better how it works and why you said "guide or seal on #2".

But I have to mention, that truck died in 2019. Henry brought this thread back from the dead, but I guess I should've told the rest of the story by now anyway.

So anyways, here is the story of the demise of my beloved old F-150...

That flashing CEL situation went away for a long time, since I never went up and down that hill anymore.

After a while, the CEL came on and stayed on, but it wasn't flashing.

She still ran same as ever, idled fine and all, but the water consumption slowly went up.

One night on my way to band practice, running a little late, she started overheating.

It was only another three or four blocks to the studio, so I pushed it. ... ... That was the straw that broke the camel's back.

When I pulled into the parking lot, it was a spectacle... Sounding like a diesel, steam pouring out from under the hood, sputtering and knocking, and a puddle of water starting up underneath...

Four hours later, I refilled the radiator and was able to make it home. About 15 minute ride, almost all highway... She was overheating again as I pulled up to my place.

After that, she was only good for five minutes at a time. I would add water and it would immediately start dripping where the engine meets the trans on the passenger side.

I wound up selling the old F-150 for $200. The guy was hoping that maybe it's just the freeze out plug, but I told him about the head issues too. I think the head was probably cracked by then.

[Jim2]

Phil gives you great advice. I make these pressure testers for this exact scenario when I am searching for a blown head gasket. You simply knock the ceramic off the plug, cut it at base and tap it for a serrated valve. Pressurize cylinder, pull rad cap and look for bubbles. This tool can also help in looking for bad valve seals and guides.

haha!!! Right on! That's friggin awesome man

I love that kind of stuff...

[Henry]

Thanks Ron, especially for your comment on the #2 plug. If you could expand on that, I'd like to understand better how it works and why you said "guide or seal on #2".

But I have to mention, that truck died in 2019. Henry brought this thread back from the dead, but I guess I should've told the rest of the story by now anyway.

So anyways, here is the story of the demise of my beloved old F-150...

That flashing CEL situation went away for a long time, since I never went up and down that hill anymore.

After a while, the CEL came on and stayed on, but it wasn't flashing.

She still ran same as ever, idled fine and all, but the water consumption slowly went up.

One night on my way to band practice, running a little late, she started overheating.

It was only another three or four blocks to the studio, so I pushed it. ... ... That was the straw that broke the camel's back.

When I pulled into the parking lot, it was a spectacle... Sounding like a diesel, steam pouring out from under the hood, sputtering and knocking, and a puddle of water starting up underneath...

Four hours later, I refilled the radiator and was able to make it home. About 15 minute ride, almost all highway... She was overheating again as I pulled up to my place.

After that, she was only good for five minutes at a time. I would add water and it would immediately start dripping where the engine meets the trans on the passenger side.

I wound up selling the old F-150 for $200. The guy was hoping that maybe it's just the freeze out plug, but I told him about the head issues too. I think the head was probably cracked by then.

JIM - MANY of us have a lot of time in that pick-me-up-truck. We were NOT going to leave you stranded! So many posts of different sets of problems. You know, that being a 6 cylinder, a head would not have been a huge undertaking; I mean everything is right there with lots of room. Yeah, I know, it's long gone but just sayin.

Lastly: Who belongs to that good looking Dodge RAM in the pic? Stay safe.

Henry