Headgasket Gone?- Help I've Screwed up!! :'(

[DreamsOfA47]

Hello all,

I've been away a while but since I posted last I've just been steadily tinkering with my 67S1A and my Type 26 Elan projects. This past Friday I finished installing my new GAZ suspension and drove the car with no issues. Later that evening I endeavored to drive it to a friends house not far from work up the freeway maybe 10 miles. Everything was going well until it wasn't! I have had issues with the cooling system in my 46 before so I'm very careful about checking T's and P's while driving and it felt as if all of a sudden my temp gauge was pegged at 120 C+ and my coolant was boiling out of the swirl pot! I pulled over and shut the car off as soon as I could but damage was clearly done. Now the engine is very hard to start and it won't idle at all nor run below 3k RPM. Interestingly the engine still seems to are you very well above 3k. All my experience as a mechanic has me pretty sure the head is warped and the gasket blown, but do any of y'all with experience with the Renault motors believe it to be anything else? I'm so very sad to have hurt this motor but I need to get it fixed ASAP  :'(

[jbcollier]

Doesn't sound good.  What's the history on the engine?  Overhauled?  When?  Run hot before?  What circumstances?

[jbcollier]

Ok, I searched your posts and can see that this is a long running issue.  Any history on the engine otherwise?

Sure, you could just do a head gasket but the gods might be telling you it's time to overhaul the engine properly.

[dakazman]

  How does your oil look ? Muddy? Clean ?
Plugs Clean black or super clean?
Dakazman

[Clifton]

You can have a HG blow into just the cooling system or between just two cylinders and have clean water/oil.  If into cooling, a cold engine will pressurize the cooling system, or preserize the cooling and it may drip into the cylinder. Visible with a bore scope. Or if between two cylinders, you will push pressure into them next. Sometimes you will have a knock on a cylinder from being pressurized from it's neighbor. Pulling a plug wire will stop the knock. Leak down testers are cheap, it would be my first check. Picoscope and a pressure sensor will tell a lot but scopes can be a learning curve.

[BERNIEHUMBER]

HI:
A little late now but at some point check your rad.
There is a baffle in the header that forces the coolant to do another pass through it.
That baffle came loose in mine and the coolant just went in and the out again.
The car over heated and luckily I found the problem before the HG blew!
Good luck!

[DreamsOfA47]

JB I have no idea the history of the engine. I have no idea when the engine may have last been overhauled or any major service performed. The overheating issues were so loved be the installation of a new rad. It was a cheap Chinese eBay rad but its been working fine for about a years now with no issues keeping the car cool. Bernie I’d be quite surprised if the baffle you speak of would have failed already. Come to think of it, I’m not sure the aftermarket rad I’ve installed has that baffle  Maybe that would be a good thing to check!

Dakazman the oil is actually totally fine and it seems that the cooling and oiling systems haven’t been breached. I haven’t checked the plugs yet but that’ll have to happen ASAP. Clifton at this point I’m believing that I have a break in the gasket or the header has warped such that I have either a breach between 2 cylinders or a breach between a cylinder and the outside. I have a leak down tester at work (I currently work as a mechanic at a shop specializing in 80s Porsche’s) and as soon as I can get the car there I’ll be able to check it out.

Please correct me if you see a major flaw in my logic here: the car was running really well before it overheated. Now that it’s overheated it barely starts. If I can get it to start it won’t idle at all. It can only be kept running above 3000 rpm but above 3 it seems to run pretty well. It’s a little down on power but it revs freely above 3k. I’ve taken up to a little above 4k in a brief troubleshooting stint. All of this leads me to believe it’s not a bottom end or rotating assembly issue. I never lost oil pressure and the quantity and quality of oil pressure seems great. I can’t imagine it would be carb related in any way. I can’t see how overheating would damage the valvetrain either. What do y’all think? I can’t see it being anything else other than head gasket or the head being warped.

[DreamsOfA47]

Here are some short videos I took of what the car is doing

https://youtube.com/shorts/Jgd2xHtoXKE

https://youtube.com/shorts/mmNvC-RVG_U

[Dreamer]

Why do you think damage was done? Is it hard to start or just hard to roll over? Does it make terrible noises? If so when, while starting, running or both? Is there smoke? Are liquids present in places they should not be?
Remember, white smoke out the exhaust is water in a cylinder and likely a blown head gasket. Blue smoke indicates oil which maybe blow by due to bad or broken rings. It may also be from valve guides.
Hard to roll over maybe due to spun/seized bearings. Hard to start and rough idle below 3k may be due to fouled plugs or timing that is out.
As others have stated, check the easy stuff first, fluid levels and condition, plugs, compression etcetera.
Let us know how you get on.

[Kendo]

 Oils any ignition problem cause this? Timing slipped suddenly or something?

I’m no mechanic, but I noticed in your summary of the problem that you have the sequence of: overheating led to barely starting. But what if, while running, something happened (like slipped dizzy) that, if you had stopped right then, would have shown hard starting. And that change led to overheating?

[BDA]

 

I hate to admit that I have had a serious overheating episode in my car (alum. head/iron block) with no repercussions. I realize that such an episode may have different effects in an alum. head/alum. block engine but I think there are things that make sense to check first - including the things Dreamer suggested.

A compression test might be a place to start if you don't have ready access to a leak down tester (I'd argue it would be worth having your own. You can buy one or make one pretty easily (https://www.lotuseuropa.org/LotusForum/index.php?topic=3696.0).

What about your ignition? Is your distributor in good shape (advance weights, point gap if you have them, etc.)? If you have a Pertronix ignition, the attached bench tests might be helpful.

Since you suspect that you have a head gasket issue but your fluids seem fine, put a microphone attached to your cell phone down one cylinder and put compressed air into the neighboring cylinder while it is a TDC (https://www.lotuseuropa.org/LotusForum/index.php?topic=4185.msg44858#msg44858). If the gasket is leaking that way, you will be able to hear it.

[Clifton]

I'm not a carb guy but do your carbs have an idle circuit? Seems to rev fine once it's up there above idle. A nice vacuum leak maybe?

[jbcollier]

Go through the basics.  Check valve clearances, do a compression test, fit new plugs (common fail point), check the points (replace if pitted) and replace the condenser (common fail point).  Check the cap (cracks and carbon tracks) rotor (shorted) and wires (high resistance and cracks in the insulation). Set it all back up and see how it runs.  Still poor?  Now look at the carb.  Plugged idle jets (as mentioned above), fuel supply (plenty of but pressure under 3.5 psi), vacuum leaks (carb base, manifold, cracked hoses).

[DreamsOfA47]

Alright y’all I have an update for you! Yesterday evening I managed to get the car to my place of employment to start running tests. So far I’ve only been able to run a leak down test and it showed as follows:
80psi of pressure in
#1 74psi - 7.5% loss
#2 68psi - 15% loss
#3 62psi - 22.5% loss
#4 64psi - 20% loss

This leads me to believe that the engine is pretty tired, but it doesn’t appear to have had the head gasket fail. JB I’m going to start working through your list over my lunch break today. I can start with plugs and we’ll see where I can go from there. Today will be the first I can work on the car with daylight so that’ll make things a little easier. Dreamer and Kendo y’all have both mentioned timing but I’m not sure what overheating could do to affect that, but I may need to begin looking there. Clifton I agree with you it definitely seems like a vacuum leak, which has me worried that the head gasket may have failed between a cylinder and and the outside world, as opposed to into a coolant or oil passage.

I’ll let y’all know what I find!

[Clifton]

Clifton I agree with you it definitely seems like a vacuum leak, which has me worried that the head gasket may have failed between a cylinder and and the outside world, as opposed to into a coolant or oil passage.

I’ll let y’all know what I find!

If it's blown between two, it would still idle but knock when the early cylinder catches the pressure from it's neighboring cylinder. I've had two that did this. Quick test is pull a plug wire. It's not this though as your leak down would have showed it. If it runs good above 3000 rpms, it's not a weak ignition. If I could place a bet, idle circuit or vac leak.