rob588cliff
Member
- Posts
- 19
- Location
- Chudleigh Devon.
Hi, I recently purchased a CCV 80 inch trialer with a 3.5 V8 (mid 80's) RR engine, running on twin SU's. The temperature gauge was faulty when I purchased it so I installed a mechanical gauge. Immediatly after installing the gauge I started getting strange readings, it would tick over for 5 mins and the gauge would show zero, suddenly it would go to 80 degrees and it would then flucuate all over the place however, with the fans on I could maintain 90 degress ish (stationary). Due to it not being road legal I hadn't been able to drive it anywhere, until a recent trial. At the trial the gauge was rockting up to 100+degress regularly, and water was leaking out of the expansion tank. I wasn't happy running it so warm so I packed in the trial.
Having since looked at the plumbing in more detail, I had two small hoses at the top of the radiator, one going to the expansion tank and one going to the top of the inlet manifold. The hose at the bottom of the expansion tank fed into the TOP hose on the radiator, this hose was almost horizontal to the ground. When I was going up hill water was running from the TOP hose back to the tank, causing it to overfill !! I completed a sniff test and that proved to be clear. I also checked the thermostat and it didn't have one......which I believe is fine in a trialer.
I have since re-plumbed the system so that the expansion tank drops down vertically and T's into the LOWER radiator hose. The other two small hoses are connected as they were, one to the expansion tank and the other to the inlet manifold. I then filled the system (nose in the air) and ran the engine. The temp gauge shot up to 100 degress, but on a positive, the expansion tank settled nicely, and wasn't being fed from the radiator hose as it was before, so no over flowing from the tank. I managed to clear the air from the system and the temp sat comfortably at 72 degress with the fans on (stationary) for a good 30 mins..........so, I think I've now sorted the over heating issue, but I guess I won't know that for sure until I attend the next trial.
However, I've now developed a new problem.......everything seems to functioning 99% correctly apart from the fact that the aluminium expansion tank is getting really hot to touch. When the engine is at 72 degress you can only touch it for about 5 seconds. If you turn the fans off and allow the temp to get to 90 degress you can only touch it for about 2 seconds. To clarify, the tank remains really hot even if I remove the small hose that goes from the radiator to the expansion tank. The heat can only be coming from the lower hose connection and/or from the heat of the engine (theres not much space under the bonnet). But, it doesn't make much sense because the engine is only running in the 70's and the lower hose from the radiator is very comfortable to touch.......where is the heat coming from ??
A couple of points worth mentioning.....I used a laser thermometer and took various readings.
Everything in the engine bay (thats metal) feels very hot. The alternator which is very near to the expansion tank was about 65 degrees.
I haven't managed to test it whilst actually driving. Is it being caused by the heat sitting in the bay due to no air circulation ?
When the top hose is around 75 degress the bottom hose is around 60 degress (this suggets the radiator is woking effectively ?), is it just convection from the water in the lower hose heating the water in the tank and the tank itself ?
There are NO bubbles in the expansion tank now that its bled properly and the level of the water in the tank is remaining very constant, this feels positive ?
The truck is running with two new, decent, electric fans.
Sorry for the long message, but I wanted to give everyone the full picture !
In summary, why is my expansion tank getting so hot.......is it just because the truck was stationary when I tested it and therefore getting no air ciculation ? I guess, if the lower hose is around the 60 degree mark, due to convection, the water in the tank and the tank itself would run at a similar temp........it just felt too hot !!!
Thanks
Having since looked at the plumbing in more detail, I had two small hoses at the top of the radiator, one going to the expansion tank and one going to the top of the inlet manifold. The hose at the bottom of the expansion tank fed into the TOP hose on the radiator, this hose was almost horizontal to the ground. When I was going up hill water was running from the TOP hose back to the tank, causing it to overfill !! I completed a sniff test and that proved to be clear. I also checked the thermostat and it didn't have one......which I believe is fine in a trialer.
I have since re-plumbed the system so that the expansion tank drops down vertically and T's into the LOWER radiator hose. The other two small hoses are connected as they were, one to the expansion tank and the other to the inlet manifold. I then filled the system (nose in the air) and ran the engine. The temp gauge shot up to 100 degress, but on a positive, the expansion tank settled nicely, and wasn't being fed from the radiator hose as it was before, so no over flowing from the tank. I managed to clear the air from the system and the temp sat comfortably at 72 degress with the fans on (stationary) for a good 30 mins..........so, I think I've now sorted the over heating issue, but I guess I won't know that for sure until I attend the next trial.
However, I've now developed a new problem.......everything seems to functioning 99% correctly apart from the fact that the aluminium expansion tank is getting really hot to touch. When the engine is at 72 degress you can only touch it for about 5 seconds. If you turn the fans off and allow the temp to get to 90 degress you can only touch it for about 2 seconds. To clarify, the tank remains really hot even if I remove the small hose that goes from the radiator to the expansion tank. The heat can only be coming from the lower hose connection and/or from the heat of the engine (theres not much space under the bonnet). But, it doesn't make much sense because the engine is only running in the 70's and the lower hose from the radiator is very comfortable to touch.......where is the heat coming from ??
A couple of points worth mentioning.....I used a laser thermometer and took various readings.
Everything in the engine bay (thats metal) feels very hot. The alternator which is very near to the expansion tank was about 65 degrees.
I haven't managed to test it whilst actually driving. Is it being caused by the heat sitting in the bay due to no air circulation ?
When the top hose is around 75 degress the bottom hose is around 60 degress (this suggets the radiator is woking effectively ?), is it just convection from the water in the lower hose heating the water in the tank and the tank itself ?
There are NO bubbles in the expansion tank now that its bled properly and the level of the water in the tank is remaining very constant, this feels positive ?
The truck is running with two new, decent, electric fans.
Sorry for the long message, but I wanted to give everyone the full picture !
In summary, why is my expansion tank getting so hot.......is it just because the truck was stationary when I tested it and therefore getting no air ciculation ? I guess, if the lower hose is around the 60 degree mark, due to convection, the water in the tank and the tank itself would run at a similar temp........it just felt too hot !!!
Thanks
