Experimenting with thermostats


#1

I’ve been having problems with my engine temps since I installed this engine last Spring. This past weekend the engine was running at 220deg. I have a huge triple pass radiator that is carefully shrouded, so I should not be seeing engine temps go over 200deg.

I don’t know for certain the history of my thermostat. Old #6 ran nice and cool. I moved the head and probably the tstat housing from Old to New #6, and I think the tstat housing got moved too. Then I did an engine swap on New #6. At some point New #6 started running hot but I don’t remember when and I don’t know for sure if I’m still running the same tstat from Old #6.

Today I bought a couple different replacement tstat’s. I noticed as I was buying them on line that they all reported slightly different dimensions. That made me wonder if some tstats have openings that are bigger than others. I’m going to pull the tstat out of New #6, carefully measure all the tstats, then put them in a sauce pan, see what temp they open at, and see just how much they open.

Maybe tstats with different size openings are common. Maybe different tstats open up a lesser amount when fully open, I don’t know. But I’m curious to find out. I’ll report back in a week.

I’m also going to get behind my radiator with some high pressure air and see if it’s full of grass or something that isn’t visible to the casual inspection.


#2

Are you using the same coolant sensor and guage? Maybe you should try running no thermostat, since your multipass radiator is probably more restrictive than normal(a not very educated guess).


#3

Our tstat housing design requires a tstat. This is because when the tsat opens up fully, it not only opens a passage but also closes one.

With the tstat closed coolant is not allowed to return from the radiator. Also tho, coolant is allowed to go directly from the head to the water pump.

When the tstat is open the the return from the radiator opens up. Likewise that direct path from head to pump is closed. As a result the only way to the pump is for water to go to the radiator first.

I know that’s hard to read, but the only way to understand it is to take a spare tstat housing, label each connection, and then take it apart and look inside. W/o removing the tstat you can’t see the port that provides a path for coolant from the head to go right to the pump if the tstat is closed.

When the tstat is removed then coolant from the head is presented with 3 choices of paths…1) to the pump 2) to the Radiator inlet, 3) to the radiator outlet. It will mostly choose 1) because the pump’s inlet is the low pressure zone of the system. Very little coolant will flow thru the radiator in that scenario.


#4

Ranger, I’m going to hazard a thought that there is an inverse relationship between your tinkering and your success. Seems like, based on the volume and variety of tinker topics that the first part of this year you tinkered less and were much more competitive. Coincidence?


#5

Certainly I was poking around lots of issues in my early days and I also went thru a lot of engines, but the connection between the two is weak. Or at least I’d like to think so.

It’s hard to remember now what the fate of all those engines were. I think the clearest link between one of my experiments and problems was my Accusump. At one point I had a temp engine with no scraper. It’s purpose was to get me thru 2 events while Chuck Baader rebuilt engine #7 into engine #9. He had built #7 but it had an oiling system problem probably related to a fault oil pressure relief valve. That temp engine, engine #8, had no oil control measures of any kind. At that time I had 3 oil pressure sensors and 2 oil pressure switches. I could see the oil pump often sucking air briefly and the Accusump often discharging oil and then refilling. But then the weird shit started happening. Once the Accusump disharged, I couldn’t get oil pressure back until the car sat for a couple minutes. Imagine sitting in your car and idling for 30secs but oil pressure never comes above zero. This only would happen when the Accusump entirely discharged, but hitting 3 hard turns in a row would indeed entirely discharge the Accusump. Then I had to turn the car off and sit for 5min. Then turn the car on and oil pressure would build as normal. It was the goddamndest thing.

Anyways, that killed temp engine #8 which I’d pulled out of an E30 I’d bought off of CL for a song. Not a great big loss. I pulled out the Accusump tho. I didn’t trust it anymore.

My Accusump ran fine for a while, the problems didn’t start until engine #8. I don’t even know for sure if the Accusump was the problem. So did my idea of installing an Accusump kill that engine? I don’t know. Maybe.

Lets see if I can rettle off the fate of each engine.

The below is a little confusing because I have 6 engines 4a-4f. That was necessary because I could have sworn that I remembered correctly the fate of engine #5 that overheated in the RA enduro. In order to keep calling that engine #5, I had to have 6 engines that want to be called #4. I think this is 18 total engines. Dang.

Engine #1. I got my car Fall 2007.

#2. Dec07 Audible rod knock leads to all bearings have to be replaced. No one told me about 1qt oil over, scrapers, baffles, or any of that. My first engine lasted 3 months. This is why I try to ensure that newbies don’t make the same mistakes I do/did. For counting purposes I called this an engine failure.

#3 Fall 08 Molitor dorks up my head. I decided that what I needed was a cherry head. So began the Molitor Saga. He built the head and installed it just prior to RA iN Dec. He then brings my car to the track and it ran like crap. I let him take it back to the shop.

#4a Molitor dorks up my whole engine. After a dozen repatitions of “your car is almost ready”. “Sorry not ready”, I get desparate to get my car back. I stake out Molitor’s shop for a week. First week of Feb, the coldest of the year, and I finally got him, me, and the cops all co-located. Got my non-running car back. Mystery motor wouldn’t start. I certainly had no idea of how to work on an engine so I took it to a local Savannah shop and they said major compression problems.

#4b The saga of the CMP engine replacement. CMP was in 3 days, and I had a non-running mystery motor. The early hero’s of SpecE30s, all of them gone now but for Robert Patton and Chuck Taylor, told me to get my car to CMP, and find a way to get an engine to CMP, and they’d get the motor swapped. Having never done anything more serious then changing my oil, this seemed like crazy talk. But I did as bid and showed up with my car and an engine from Strictly German. We swapped it Saturday morning in time for me to race Sat afternoon. It was epic.

In Fred Switzer’s defense, he was also there, he just wasn’t one early hero’s. Fred and I just kinda helped around the perimeter doing specific tasks as directed. Like holding cold drinks and wiping brows.

#4c. The Strictly German engine was weak. I pulled the head off and sent it to Metric Mechanic. One way or another I was going to end up with a cherry head. MM called me back and told them I’d sent them a 323i head. There went my core fee. I called Strictly German and told them about it, but I think they just perceived me a nut.

#4d The MM head fails. When my head came back from MM I put it on and it had lousy compression. I really had no idea what I was doing. I was way outside my experience zone putting a head on, or doing compression and leakdown tests. I also did a drip test on the MM head. I was sure that I was just doing it wrong. MM was sure that their head was fine, since they do them all the time. So night after night for a month I’d install the MM head and do some tests, then the next night I’d install one of two take-off heads, and do the same tests. I was trying to figure out what I was doing wrong such that the MM head was failing. It was very frustrating. I got to be pretty good at R/R’ing heads tho. Finally I put my foot down and told MM I was shipping the head back. Doing all of these tests on these different heads night after night I could not find a way that the MM head proved to be ok. Either it was screwed up somehow, or I was losing my mind.

4e. The MM head is killed. MM called me a week later and said they found that all the valves seats had been improperly ground on my head and they all leaked like seives. The problem was that altho they do lots of M20 heads, they almost never do one to stock specs, so from their perspective my head was kind of a one-off. Something got miscalibrated and it came out wrong. They sent me another head.

I picked up my block and pistons from my machine shop and took everything to a local race shop that had agreed to allow me to participate in the build. I learned a lot over the next 2 days, but the primary lesson was to have one shop responsible for all aspects of an engine build. MM did the head, a machine shop did the block, and now I had a race shop doing the build. I wasn’t at the shop when the head went on the engine. The shop somehow mislaid the head’s rocker arm shaft retaining pin, and not being familiar with M20 heads didn’t notice. It was at Road Atlanta the next day that the shaft turned, which moved the oiling holes and the cam cut the head up for lack of oil. I think a couple rockers busted too.

4f. MM takes pity on me. To the surprise of MM I called them up a couple days later and asked them to build me another head. They were pretty mortified at what happened. The next day they called me up and said that they were building me a new head at their cost. And that’s why I’ve always been a big MM fan. They really squared me away that day. I’d been going thru huge money and between the Molitor saga and head struggles, I was running low on enthusiasm.

#5. Dec09? This engine failed at RA in an 8hr enduro. It had my “at cost” head and was a perfect engine. It was killed by a slow coolant leak out of the hose that feeds the throttle body. I wasn’t driving it at the time. This is why I remove all coolant hoses that I don’t absolutely have to have.

#6 Feb09. This was #5 with it’s head repaired. After asking everyone I knew what I needed to do to fix #5 I pulled the pistons and “inspected” their rings. The rings looked find to me so I re-installed the pistons. That “inspect” the piston rings that my betters guided me to do was bad advice. What they should have told me is “replace” the piston rings. Once I put #6 back together it ran for 2 laps and failed with no compression.

#7 Apr09. The engine that never had good oil pressure. Chuck Baader built this engine. As bad luck would have it, something prevented it from ever having good oil pressure. I ran it a couple months and then shipped it back to Chuck. The problem might have been the oil pressure releif valve, which had probably come from my #5. I don’t know. Sometimes lady luck is with you, and sometimes not. Chuck replaced the bearings and oil pressure relief valve and all was well.

#8 May09. This was my temp junkyard motor I used for an event or two while Chuck turned #7 into #9.

#9 Jun09. This was a great engine.

#10. The first MM engine. In early 2010 Rich Bratton and I spent a week at MM. It was really terrific. We were guests in their house and spent 18hrs/day with them in the shop. Totally awesome. Rich came back with a full engine and I came back with 2 bottom ends. For no good reason I pulled #9 and put in one of my MM engines. #9 became a spare and sits in the garage to this day.

#11. Feb12 New #6. I had #10 when I went into the wall at RA in Dec11. A week after the crash I bought and ugly duckling GTS2 E30 and converted it to Spec. The engine that came with that car was #11.

#12. Apr12. #11 was weak. I was afraid I might have bent the crank of #10 so I installed the 2nd MM bottom end.

#13. Early 2013 I pulled the head and did a slight refresh of the valve-valve seat seal with some honing paste or whatever you call that stuff.


#6

Ranger,

Has anything else changed?

Particularly lower section of the engine compartment. Did you change/install a skid plate, or change any of the airflow through the lower header panel…etc.

The reason I say that, is I saw a 20-30 change in average temps after changing the skid plate to a more solid design (no holes for airflow.)


#7

Has anyone verified that a non modified OEM replacement water pump is capable of supporting a triple pass radiator? How old is the current water pump? My advice would be KISS and install a standard radiator and see what happens.


#8

I agree with the KISS principle as far as oiling is concerned. That is why I delete the OPR and modify the oil pump. The best way to loose oil pressure on one of these motors is around the cam…loose cam in the head. You can also add restrictors in the spray bar to help.(that, of course, assumes good bearings!!)

Water pump should not be the problem as long as the impeller is intact. If you have water pressure, you should be moving water. Of the cars I build, I always used the 176 degree thermostat as I found on the dyno that these motors dislike temps over 180 degrees. That said, I also block off the rear head water fitting and the spigot on the thermostat housing.All other hoses are OEM stock. I use the “i” top hose with the “e” bottom on a double pass radiator and every motor I’ve done this way runs at the thermostat temperature.


#9

[quote=“djjerme” post=77345]Ranger,

Has anything else changed?

Particularly lower section of the engine compartment. Did you change/install a skid plate, or change any of the airflow through the lower header panel…etc.

The reason I say that, is I saw a 20-30 change in average temps after changing the skid plate to a more solid design (no holes for airflow.)[/quote]
There’s plenty of air getting to the radiator. And altho I’ve made changes to the air dam that limited air coming to the rad, and also added shrouding to force the air to go thru the rad, neither changed the symptoms.

Now that I’ve really sat down and studied how the tstat and tstat housing work, I’m kinda wondering if I could have put the tstat in backwards. I think it will fit backwards so it’s possible. I totally remember having the tstat in my hands last Spring and wondering which way it went. If the tstat was backwards it would only half work. That is to say…flow thru the radiator would be blocked until hot, but rad bypass flow would never get diverted. It kinda fits the symptoms. I’ll be checking soon enough.

[quote=“cwbaader” post=77351]I agree with the KISS principle as far as oiling is concerned. That is why I delete the OPR and modify the oil pump. The best way to loose oil pressure on one of these motors is around the cam…loose cam in the head. You can also add restrictors in the spray bar to help.(that, of course, assumes good bearings!!)

Water pump should not be the problem as long as the impeller is intact. If you have water pressure, you should be moving water. Of the cars I build, I always used the 176 degree thermostat as I found on the dyno that these motors dislike temps over 180 degrees. That said, I also block off the rear head water fitting and the spigot on the thermostat housing.All other hoses are OEM stock. I use the “i” top hose with the “e” bottom on a double pass radiator and every motor I’ve done this way runs at the thermostat temperature.[/quote]
For all: I learned a lot from Chuck over the years. He’s been racing e30’s longer than any of us I think.

When Chuck says “loose cam” he means the bored holes in the head that the cam journals run in. Because the holes are only AL they wear easily. Wear in those holes is what most often turns a head into junk.

For Chuck. Don’t forget the throttle body hoses. That’s what killed #5.


#10

Which water pump/overflow set up do you use? Early or late?


#11

I had issues all weekend with temps getting as high at 210. Engine lays down at those temps. My oil cooler is in front of rad as is a pusher fan. The pusher fan is spinning at high speed. I know this because the indicator light on the dash starts to glow so it’s spinning and generating current. I think the rad is just not getting enough air so I’m starting by switching to a puller fan. No idea what thermostat I have and I’m sure Chuck you can’t remember (you usually take a guess at what you had for breakfast so I know a 2 year old thermostat has left the memory banks long ago).


#12

It’s not the fan. Look for another cause.

The first think I’d look at is radiator shrouding. Rig up something that prevents air from moving around the top/bottom/left/right of the radiator. There are OEM plastic pieces for 3 of 4, but they are usually long gone.


#13

210… That’s what my car runs at normally.

I guess the question then becomes where are people taking their temp? Mine is in he stock T-stat housing.


#14

Brian…I do remember…176 degree. I don’t remember the radiator, though. Ron Davis double pass? Motor absolutely should not run that hot…it should run on the thermostat as every other car I have built.Fan and oil cooler placement irregardless! Last car was a chump car making over 200hp at the wheels and it runs on the thermostat. There is another problem somewhere which could be the thermostat itself. Where did I pick up the water temp? Top hose?

Water pump does not matter…I have used both old and new, but mostly old with water tank on RF fender.

On edit, I have never used radiator shrouding, although it could not hurt.


#15

Rad is a Ron Davis. Yes water temp is top hose. Idleing with fan on and water wetter is 170-180 but it will creep to 185 and it can’t hold 185 on track.


#16

New thermostat showed up today. I pulled off the tstat housing and put both tstats in a pan of water on the stove. I used an IR gun to measure temp. I also attempted to measure how much opening each tstat created when fully open.

I really didn’t learn much. They both started opening around 176ish and were fully open at only a couple degrees higher. They both seem to open up about the same amount so no difference in water flow rate. What’s the opposite of “eureka?” I’d hoped to find something interesting.

So I pulled the aftermarket triple pass radiator out and I’m going to take it to a shop that welds aluminum. The bottom port is at a bad angle and it kind of crimps the rubber hose. Maybe that crimp is limiting water flow more than I thought. The shop can cut the port off and weld it at a better angle.


#17

The opposite of “eureka” is “I’m not as smart is I thought”.


#18

Chuck Baader asked me to post this pic of his setup. That’s an oil cooler on the L side.

[attachment=2047]DSC_0802.JPG[/attachment]


#19

This has been my standard for over 10 years, without cooling problems…that is, except tor Brain’s car. I’ll try to look at again and see if there is anything obvious.


#20

Our thermostat seals against the head blocking that port yes, but when open, the entire Tstat housing fills with water and the only thing dictating path of flow is the pressure differential itself. There is nothing in the T-stat that seals off the short return route to the WP from the cylinder head.

I realize I’m 4 years late to this post, But I came across this and like to try to correct misinformation.