Temp up and down after coolant flush

First. The last post on this thread was 2 years ago, but you still might get a response from the OP.

Second, where is the mechanical gauge source located?

Third, does the TEMP light come on when it hits 260?

A spike of 60 degrees in 5 seconds seems a bit much of a realistic swing.

Lastly, if you have a correct pressure radiator cap and a recovery tank, fill the recovery tank to about 3/4 full and get the car to full operating temp, then shut it down and let it cool completely and see if the level in the recovery tank drops. If so, it is pulling the coolant in and will "self purge" the void in the system.
(Not always, sometimes trapped air will still exist, but I have never had trouble with trapped air with a correct system that holds pressure and a good cap, and overflow line.

 

Good points here but issue does not reside on questions raised.

Mechanical gauge installed on B4B manifold, at the front water crossover driver sider. The mechanical gauge installed location is lower than the original sender (electrical), which is installed on the same crossover, passenger side. The electrical sender does not move like the mechanical gauge on these wild swings (appears to be far less sensitive - much higher response hysteresis I believe, air.... pocket does not "pass / sit" there despite being the highest point of manifold? Unlikely, but I do not know....). Riviera 67 does not have temp light, only a sender and needle on panel. Sender works fine (also replaced, behaved like the previous one that was installed prior engine being removed).

A spike of 60 degree in 10 seconds CANNOT be real coolant temperature indeed - it has to be air pocket somewhere that when gets into the sensing point, causes the erratic reading.

Radiator cap (2x) tested good at 13psi (both say 16 PSi, but testing gear is cheap Chinese). 13 PSI would be fine for real coolant temperature of >230 - cap is not the issue.

I do not have a recovery bottle - need to install one later... But I believe this topic cannot be an issue, since the problem manifests multiple times on the run after the radiator was full with procedure of bleeding with cap off for a length of time, thermostat open, rpm, etc - so there was no chance "to lose and recover coolant" in a single cycle. But agree - it does help on longer term.

Further thoughts?


Cheers/Alex

 

Larry, can you elaborate on the combustion leak into the coolant topic, how does it happen, what signs to look for etc. How do you test for hydrocarbons?

 

Hmmm interesting. I've combated engine cooling issues for a while now and have them mostly under control but like the OP and the other fella I too experience them spikes at times. No where near the extreme as them, mine usually operates around 190-195, some days it's 195-200 but will spike up to 205-210 for a few seconds then drop back down. I've had a feeling deep in my mind about a cracked block or a head gasket failure happening being a possibility but never knew how to test for that. Even though I'm building another engine I think I will test the engine just so I know and I do need it to last a bit longer until the new one is finished. Thanks Larry

 

Radiator looks original, copper, etc.
But crack is something i was thinking about too (but in denial...). I did not check heads or block for cracks. My 430 engine was a 66-year made. I heard about the higher odds of these heads cracking but when i had then out, just changed springs and did a bit of valve job and not shop magnaflux (home-made overhaul...). I guess a leak test may be on order. If cracked, i guess i will have to start my new engine and heads project soon with JW
Will do this test and revert to forum. Cheers/Alwx

 

1. An air pocket in the water jacket would make the temp gauge read LOWER than true temperature if the air pocket was in the area of the temp sending unit. For practical purposes, air pockets don't exist in one of these engines once the thermostat opens (unless the "air" is combustion gasses that are constantly being generated.) The engine is installed at an angle, the thermostat is the high point of the engine. Air rises, gets blown past the thermostat into the upper rad hose by the flow of coolant, and probably into the radiator where it's seen as "low coolant level".

2. Solder bloom is not the only thing that can clog a brass/copper radiator. It's perfectly reasonable to think that mineral scale or oil contamination can be cleaned-out.

3. Plenty of defective radiators are defective because the AIR FINS aren't in good contact with the coolant tubes. The coolant tubes can be perfectly clean, but if the air fins aren't in good contact, the rad won't dissipate heat like it should. We see this a lot on radiators from salt-in-the-winter states. The road splash from the vehicle in front puts saltwater on the radiator behind. The air fins corrode until they don't contact the water tubes.

4. In this particular case, I'd be more suspicious of the GAUGE and less suspicious of the VEHICLE.

 

1) Radiator may well be clogged in some parts for sure and one would not be able to clean it properly - agree (I just hosed it - meaning washed until water came clean...). However, the car temperature behaves well at either idle and cruising conditions, so, despite it likely having a reduced cooling capability, it appears to still be attending heat removal function to an acceptable level. Another piece of information for the puzzle on this end: driving the car at 40-50 miles/hr, temperature is steady at 185-190. If I do 2-3 consecutive full throttle blasts to 60-70, and return to the 20-50 mile range, two different outcomes would take place:
a) The temperature increases slightly to some 190-200 range, stays there for a minute or so and comes back to the 185-190 range (a normal behavior I'd expect).
a) The temperature initially goes DOWN to some 160-170 (well below 180 stat setpoint) for some 20 seconds, then goes up crazing to 240-260 in 2-3 seconds, swing meaninglessly there, and reverts to some 200 degrees after another 30 seconds and start stabilizing at the 185-190 range again. My over-analysis: water pump pulls the radiator coolant in a hurry, which is cooler than stat setpoint that get slammed, some hot spot in the head now may boil coolant locally thermostat does not open immediately, etc - long and complex shot, I cannot explain what is going on here. But air in coolant would behave erratic - this is a fact.

2) The idea of engine crack and leak on the coolant system is a possibility, but i'd imagine a lot of gases coming through in a typical case (I am still going to test for it though).

I'll get a temperature sensor and start probing different points of the system systematically to try ascertain what is going on.

Sorry to pestle you guys with my problem but thought it just may be good learning / sharing experience for other in the future!

Cheers/Alex

 

Are you sure about your gauge accuracy?

 

1) Some photos of the arrangement. There, one can see the upper hose will trap air despite filling the radiator to the neck - which does not look correct to me, hence the chase for e new hose and stat housing with correct (?) angle and neck length for the car.

2) After filling up to the neck and driving the car, my radiator level was sitting at some 4in below the cap seat - very low, just covering the stat! Filling up the radiator again and slowly, I could see a few bubbles coming from the 3rd fin below new level - indicating the fins are blocked to a degree (their edges do not look clean, have some white scale). Time for a new radiator...... What is a good brand and/or type I can buy?

3) My car was always from San Diego, now it lives in sunny and dry Perth/Western Australia. The car came with a somewhat new "Evans" coolant sticker, so I assume the previous owner did something on cooling system prior "my tenure starting in Mar/2019". I never had any issue (than I knew of) because the car just had the original sender and this behaves well.

4) The gauge I installed is a new Autogauge mechanical and this mercury (?) design is reliable piece of instrument - but that is sure another (unlikely) possibility to think of. I will probe the system with a small thermocouple to check temperatures across the system.

Thanks all for your input, really appreciate it!

 

180, I did test it on water and open and 180, fully open at ~195. Did a few cycles, it is working fine. I did drill a 1/8' hole on the old and new stat thoug, maybe I shouldn't (do not see how this could be an issue but anyway).

 

1/8 hole will not be problem, and can assist in ridding air.

There are some stats designed with bleed hole(s) and in the real olden days, restrictor (washers) were use before thermostats, and many oval racers still use them.

Its about flow control to reach and maintain correct operating temp, and that small hole is insignificant to that end.

 

That is something that makes sense which I never did, based on the expectation that running thermostat hot for a while and throttling RPM a bit with the cap off will suffice to get rid of air. I will drain the system and start over again doing a "first principles" bleeding procedure.

 

I don't see this as a big concern. The hose is not much above the radiator. It may be the high-spot of the system with a potential for holding air, but coolant flow will still tend to move the air to the radiator.

Even if there's air in the hose, it's not stopping coolant flow.

I think this is a non-issue.

You don't have a recovery tank. The radiator is going to puke out fluid the first time it gets hot. The rad tank is probably stamped with a "Fill to this level" indicator inches below the rad cap seat.

Tubes, not fins.

Lots of love for GOOD aluminum radiators. MOST aluminum radiators are Chinese junk that have poor assembly or restricted flow.

I'm more suspicious of the gauge than I am of the engine temperature.

Autogage is Autometer's discount line. Sort of like StreetFire is MSD's bottom-feeder products.

It won't be a mercury design. Probably an ether-filled bulb on the end of a sealed metal tube.

 

OK, learnings from the exercise to bring it to a (temporary) closure - all finally seems good now.

Yesterday I installed a recovery tank and new 19-in derale rigid fan and termostatic clutch. I went for a ~1hr drive and temperature did not swing erractically anymore! Temperature maintained between 185-190 on city drive and 190-200 at freeway drive (all with air-conditioner running). After a few consecutive full trottle accelerations from 55-70, temperature goes to 210-215 and returns to previous range in some 30 seconds.

The bad:

Car was pinging lightly at half and full trottle when ~195deg hot (had 34 mechanical, some 7-10 degrees vaccum last time I measured). Retarded distribuitor a ted by hand and pinging situations stopped alltogheter after repeating tests. This appears to be a legacy issues from standard 430 piston design - so I read in his forum.

The coolant temperature response for the type of drive / ambient temperature / etc appeared a bit slughlish and on the high side for the 180deg thermostat being used - so a new radiator (now that one can read temperatures correctly) seems to be necessary for hot Australian summer time.

The good:

The new thermostatic fan is way quiter than the previous rigid one and "silence is golden" in the Riviera. I can now hear other engine noises I could not before! It may not "pull as much air" as the former but I will use the clutch arrangement to keep things quieter.

What I was doing wrong:

Without the recovery tank, transient conditions caused by air in the system seems to have pushed coolant out and in excess from the radiator. Every time I returned from a drive, the level was sitting some 4-5in below cap height, barelly at the level of thermostat. I installed the recovery tank and level kept where I left (1-2in below cap) after the drive. I also did not fill up the completelly to the cap, but left a expansion volume from start...


It all woked out well, thank you for helping!

Cheers/Alex

 

When I bought my 71 Skylark 455 in Sydney I drove it 600 miles home and the temp fluctuated the whole trip home from 80-120C
Without showing any external signs of overheating.
On arrival home I boiled the thermostat and observed it was occasionally sticking, not all the time but.
Replaced it and problem solved.
Still will get hot if idling a long time in the lineup at the Drive In movies like 45 mins but in never blows its stack .
A backup thermo fan would solve that I'm sure.