TR4/4A Seems like a bad cylinder head or head gasket but what do you think?

[tdskip]

Hi guys - hope everyone is having a good Superbowl Sunday. I took a break from making a copious amount of guacamole to play with the '66 TR4 and the "new" donor engine to see if I could get it fired. It did fire and oil pressure came up (not a surprise as I had oil pressure when cranking it with the plugs out) but I immediately noticed some not so encouraging exhaust escaping from the top of the engine.

This engine is not fully set up as you can see from the picture below, and isn't even running a cooling system now since I wanted to make sure it fired briefly without any bad noises etc before spending any money on it (obviously I'd not running for more than a very short time without the cooling system working). The thermostat assembly is loose fitted and the heater hose assembly is off. When it fired I noticed smoke coming from the heater hose opening and from the thermostat assembly area after it ran for about 20 seconds. Specifically, there was wispy smoke from both areas where the red arrows are pointing that was venting out as it ran.



This engine has sat for a long time so I don't believe there is any moisture that would of been evaporating from the head. Maybe being run after sitting for that long stirred some stuff up I supposed, but without the water pump spinning there wouldn't have been anything moving the air around except heat.

So it would seem that exhaust is getting into the cooling system, which makes me think cylinder head or head gasket, what do you think? Ideas?

Thanks guys!

 

[KVH]

It would have to have sat an awfully long time for all coolant to have evaporated from even the cylinder areas between the block and sleeves. Are you sure it was all dried out. I'm not sure, but what other symptoms have you had to point to a bad head gasket?

 

[tdskip]

It would have to have sat an awfully long time for all coolant to have evaporated from even the cylinder areas between the block and sleeves. Are you sure it was all dried out. I'm not sure, but what other symptoms have you had to point to a bad head gasket?

Hi - thanks for the note back.

I believe it has sat for at least 10 years in SoCal. I like your suggestion however as it means all might be OK!

I didn't smell the wispy smoke to see it smelled like coolant. When I spun the water pump by hand I got a bit more even through the engine was off.

I just assumed that with no coolant it had to be exhaust.

 

[TR3driver]

Gycol (antifreeze) evaporates very slowly, especially inside a container with a limited opening (like an engine), and especially mixed with the sediment that tends to collect in the back of TR engines.

One way to be sure would be to use one of those "block tester" things to sniff the thermostat opening. If the chemical turns yellow, that's probably exhaust you see.
https://www.ebay.com/itm/Engine-Blo...:g:pngAAOSwNNxWFXFW&item=371542001655&vxp=mtr
(Just an example, you also need the chemical that goes inside.)

 

[TomMull]

I'm not a fan of running engines without coolant, particularly wet liner ones. I'd hook up enough of the cooling system to run it. Perhaps also inspect and change the head gasket while you're at it. Easy enough to do and not too expensive. Tom

 

[tdskip]

Hi Randall, thanks for the additional info.

I'm going to cross my fingers and work on the assumption that it is old stuff burning off.

Thanks!

 

[tdskip]

I'm not a fan of running engines without coolant, particularly wet liner ones. I'd hook up enough of the cooling system to run it. Perhaps also inspect and change the head gasket while you're at it. Easy enough to do and not too expensive. Tom

Hi Tom, I've only run it for 20 seconds at a time after it was cooled down. Not going to do anymore until cooling system is set up based on the above.

 

[TR-3rg]

Hi,

Can you pull the plugs and run a compression check?

Roy

 

[tdskip]

Hi,

Can you pull the plugs and run a compression check?

Roy

Hi - I've got a pretty even 100 +/- 5 across the board BUT that was before the engine actually fired.

 

[KVH]

Hi - I've got a pretty even 100 +/- 5 across the board BUT that was before the engine actually fired.

I'm not the expert on compression, but during my last test I had 175 across the board, all four cylinders. Consistent range in all 4 cylinders is very important, but consistent low would be a concern. At 100, that just sounds low to me. Can anyone else comment on that?

 

[trrdster2000]

It seems low to me. If it doesn't come up after putting a couple of squirts of oil in the cylinders I would be pulling the head. I know rings need to be set on a engine that has not ran in a while, but that was low numbers even at that.

Wayne

 

[tdskip]

I'm not the expert on compression, but during my last test I had 175 across the board, all four cylinders. Consistent range in all 4 cylinders is very important, but consistent low would be a concern. At 100, that just sounds low to me. Can anyone else comment on that?

Good morning. That is low but the engine has not run in a long time. I am not going to worry too much about that until it has been heat cycled several times. Cold after sitting a long time is not necessarily a good indicator in my experience.

175 sounds like a very happy engine to me, was it newly rebuilt?

Thanks!

 

[jfarris]

You are in the perfect stage to perform a leak down check versus a compression check. Usually, he hard part about a leak down check is getting the piston to bottom dead center with the valves both closed. I would just take all the tension off the rocker arm and all the push rods, thus closing the valves. You need a"leak down" checker, I think mine is a Longacre and cost around $75, plus an air compressor that will put out 100psi. One of those mechanic's stethoscopes will help. Take the solid rod off and just use the open hose so you can hear the hiss of escaping air. Google "leak down" and let the fun begin.
Good luck!

 

[TomMull]

I'm not the expert on compression, but during my last test I had 175 across the board, all four cylinders. Consistent range in all 4 cylinders is very important, but consistent low would be a concern. At 100, that just sounds low to me. Can anyone else comment on that?

Lots of variables, gauge included, but I wouldn't expect much more from an engine that sat for many years. Should run well with 100 and most likely clime after being run for a few hours.
Tom

 

[tdskip]

Lots of variables, gauge included, but I wouldn't expect much more from an engine that sat for many years. Should run well with 100 and most likely clime after being run for a few hours.
Tom

Hi Tom, was thinking the same thing. If it isn't smoking and I have compression and oil pressure and that compression thinking I am looking OK right now.

 

[Got_All_4]

But some Sea Foam or carb cleaner in the cylinders for several days and good chance it will loosen the compression ring if it's all gummed up from sitting. Do your compression check and if still low then try some 30 weight oil in the cylinder and retry the compression test. If it goes up you still have a worn or stuck compression rings.
I like the idea of several hot and cold cycles so I'd fill it with water and get the cooling system sealed up so it can run a while hot. I would do the Sea Foam thing in between a the cycles.

 

[tdskip]

Thanks.

I am going to get cooling system set up at this point and take it from there.

Thanks for the info and coaching guys, appreciate it.

 

[vickxxx]

I'm not the expert on compression, but during my last test I had 175 across the board, all four cylinders. Consistent range in all 4 cylinders is very important, but consistent low would be a concern. At 100, that just sounds low to me. Can anyone else comment on that?

That is a low reading. But the compression read should be taken with a full warmed up engine to be accurate. Since the engine has been sitting for so long the usual procedure of some oil in each cylinder, oil on the tappets, fresh coolant should be done before firing it up to running temperature.

 

[TR3driver]

And as Tom alluded to; there are many variables other than the condition of the engine that affect the pressure reading; even whether there is a storm blowing in! So what you are really looking for is how well the readings agree with each other.

Also, I've seen a lot of leaking head gaskets that do NOT show up in a compression or leakdown test. Peak cylinder pressures are much higher in a running engine, and sometimes the gasket only leaks under the higher pressure. That's why I bought the "block tester", so I could be certain whether the problem was a combustion leak; or something else.

 

[tdskip]

Good discussion- thanks. Will be a couple weeks before I have time to properly run it, so watch this space.

Thanks!