The fan moving, yeah, I know what you're talking about, it's pushing the piston back down into the bore.

I typically use a plastic straw - something solid yet soft - to feel when the cylinder is at the top. A 15/16ths" socket on the dampener helps for fine adjustments.

I have heard of a situation where the head gasket blows in between two cylinders but will need to do some investigating.

Were you experiencing a loss of coolant?

Is there oil in the water (or vice-versa)?

It's good that you had all the plugs removed, makes determining things like this easier.

I have this same 400 engine, too, and both of my heads were cracked but they were cracked in between the two valves of particular cylinders (where the silver scratched area meets the non-silver area below):




Let me do some investigating, gonna ask my engine-rebuilder friend about it.

There are more pics in my Gallery if you're interested.

 

Talked to my friend, he says it sounds like a blown head gasket.

The same situation should exist when pressurizing #5 - you should feel/hear air coming from #6.

You also might see bubbles in the radiator as the water jacket passageways are fairly close by (water flows in the small holes, bolts go in the big ones):



Of course, this opens up a can of worms; when you get the head off, you may discover that it's cracked. And, oh, BTW, the compression is kinda low, implying the engine is pretty worn. Then, you get into boring & pistons & bearings and all that, this can cost a fair amount all together.

You might search Craig's List or some such for a pair of known-good heads.

So, if it were me, I would confirm that this situation in fact exists. A true leak-down test would measure the percentage loss over time.

How do the plugs on 5 & 6 look as compared to the others?

#5 has lower compression but it's not hugely low and is within the 10% margin of error but it just seems more than coincidental....

 

The porcelain cracked off of #5 but otherwise looked ok, #6 had a fowler on it that I didn't remove.

I don't know if I was actually losing coolant or if it was steaming because it was getting hot. I don't have any sign of coolant at all in the oil (just changed it and it's clear, was black before change). There was a little gunk in the radiator when I cleaned it but it was kinda pinkish green/yellow, not the grey chocolate milk color. I'll watch the coolant level closer to make sure, will be easier with my makeshift reservoir.

I took the truck to the car wash but it was getting dark so I missed a little that I would have liked to have cleaned, but as of yet I'm not seeing any real signs of any external leaks. I did notice that the exhaust on the drivers side (problem side) had a little smoke coming off ,or out of it, but it wasn't a lot and was almost hard to track down except it was night and I had a small lamp under the truck (woulda been hard in daylight).

This was after I ran a can of Seafoam through the engine since there was a bunch of crud on plug #8 I wanted to do my best to clean the cylinder. I got a LOT of carbon smoke out the tailpipe (as is usual but this was more like the first time I did this).

I still have the Thermostat out and the guage hasn't gone much over the beginning of the low Normal | \n*ormal/ |

My step brother had an offer from someone to do all the work for $500+ parts if needed $2-300 each head, and $40 gasket set, so up to around $1100+tax. This would be refurb heads from a parts store so unless the block is messed up I shouldn't have to worry, but if a head is warped but not cracked I don't know if he can fix it. I find it hard to pay anyone $500 for something I can do....even if it takes some learnin.

I wanted an older truck so I could fix it myself, so I guess I might have to tear it up. Might take another unrelaxed vacation this year.

 

another thing that can be part of the overheating is if there is a bunch of crud in the block , if you can knock out the block plugs and then flush as much as you can with a hose or pressure washer ! yup another stupid thought !

 

Is this under your normal driving conditions? If so & it seems consistent, you may just have had an incorrect or faulty thermostat.

Incidentally - apart from testing etc, there is nothing to be gained from running with no thermostat, despite casual advice you may be given to leave it out.

There is a tester for the presence of carbon monoxide in the cooling system (indicating a blown head gasket into the coolant)

 

I thought I checked all the parts stores for the CO tester, but I'm gonna check again. Only Carquest had the kit and they wanted $50 for it, think I checked the rental shops (Oreilly's and I think Autozone) and they didn't have it for rent. That was last year worth another check.

City driving up to 40mph not the highway driving where I have the main problem. Also it was only for about 30 minutes. So gonna have to drive it more, just got it back together last night and drove to Walmart and the car wash (about 7 miles)

 

I wouldn't run it infinitely without a thermostat; it serves to restrict or slow down the coolant flow, this allows the fluid to spend more time in the radiator getting cooled.

If the coolant is constantly getting redirected back to the hot engine without having the opportunity to to be cooled, the engine can *still* overheat (most often during highway driving).

This tidbit comes from my engine-builder friend.

 

This is what I was meaning - mightn't have been very clear.

 

I was so worried about getting the bolts off the heads I apparently overlooked the push rods and lifters in the book. I see a number of people saying it doesn't matter, but after removing these parts I saw they all looked the same and tossed them into a box. I was told today that I should remove them in order and tag them. oops. All the rods are the same length and they "appear" to have the same wear or at least not noticeable difference when I line them up the way they should go.

How bad is this really? Is it something that will likely be ok with a chance of bad, or is this just epic fail? Again, some posters around the web say they never had a problem if they were the same length, were they just lucky?

Ironically I tagged EVERYTHING else, but it was 11pm and they all looked the same...

Also would replacing just the rods or rods and lifters work, or would I need a new cam? If it's that big a deal I'll just try my luck and if the engine blows I'll replace the whole thing since they come installed (vs $700 for 1 of the full kits with cam)

(right head has 2 stubborn bolts on the exhaust, then I will know if it is blown/cracked, but gotta go to in laws for father's day now)

 

I think you'll be ok. But, it wouldn't be the cam that would have problems but the rocker arms and/or the lifters. The cam interfaces w/the lifters, not the pushrods.

I have a bundle of pushrods that I may use in my upcoming rebuild if the ones in the engine that I overheated don't look good. And, since the PO pulled them out I don't have a clue which ones go where. Further, they are coming from one engine and going into another with different lifters and rocker arms. But, I'll still do it if need be.

 

Thanks, the driver's side head/gasket both look good to the eye, no discoloration on the head/block, and the gasket looked good although a bit of carbon buildup in one cylinder. Cylinders had no holes.

I felt the cylinder walls and they seemed to be fine, but I will check again after I clean the carbon out.

6 seemed to have a little extra carbon, I think this one had a fowler originally but I replaced it with a new plug a week and a half ago, it looked like it was burning fine now. Maybe piston ring? 8 has a little crust around the top of the wall, but seemed fine otherwise(couldn't see it at first, but felt it).

Gonna do the other side today or tomorrow.

 

My 351W 1983 truck used to overheat like crazy. The radiator shroud was missing, and it had a flex fan on it. I hate flex fans with a passion, so I got lucky and found an OEM shroud, and fan on a junkyard truck... I got to be the first to pick parts from this truck, too!

I went to the auto parts store and bought a new fan clutch for my truck, as the one that came with the fan was leaking.

This stopped my truck from any and all overheating. It runs slightly above the middle of the gauge with the A/C on, and a hot day in traffic. The coolant runs right at 200 degrees, checking with a real gauge.

I sure hope you get your truck running right. It's awful not knowing when the old thing might overheat!

 

It looks like the initial diagnosis of good gasket, was pretty far off upon further review.

Again. I had no mixing of oil/coolant.

*Red- 3 round spots left by the gasket, all 3 look filled in on CTB's block pics. also the square at the top right looks filled but there is a hole on the head.
*Yellow- I think oil was leaking from cylinders 6/7
*Blue-This hole (only the gasket, not the hole)was actually completely covered with calcium/silt/whatever that white stuff is. (pic below)
*Green-Obvious
*Pink-I think this is where the water was leaking down the block.


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*Purple- This lines up with the non-existent square on the block.
*Blue- Looks like a chip out of the head?



I didn't get a chance to clean the head yet, but I'm pretty sure I need to replace it (mechanic also told me that he's thinking head problems from the gasket).


Still gotta do the other side.

 

Compare your pix to those in my gallery, they don't look anything at all alike.

When you reassemble everything, ensure you put the gaskets on correctly; there should be a big FRONT stamped into 'em.

A good engine builder will show you all kinds of neat things that can be learned by looking at 'em in an un-cleaned-up state.

It looks to me like you're not the first one to have been inside this engine...

 

If that head could talk...