1982 Cadillac Seville review from North America

HT4100 engine problems.

Overheating.

Engine knocking.

Underpowered.

Cam wear.

Accelerated engine wear.

Rapid oil consumption.

Unfortunately, the HT4100 engine had an aluminum block with cast iron heads. The coefficients of expansion caused most of the bolts to come loose allowing antifreeze to leak into the oil pan. This caused critical engine wear. Porosity problems from GM's die cast process added to the self-destruction of the little engine.

The concept was great, small and powerful. Early on, mechanics began noticing what would be called a "milkshake" appearing at the bottom of HT4100 oil pans. It was a mixture of oil and antifreeze. The lubricating qualities of the oil were reduced to zip and camshafts were ground down to zilch in short order. GM sought to cure the porosity problem by Loctiting the blocks however, unsuccessful. Making matters worse, the transmission was highly problematic.

I did an extensive investigation of the problems that caused the HT4100 failure and the reason for the failed class action against GM for the HT4100. Anyone interested may contact me for my special report on the horrors associated with the HT4100. Contact APNewsletr@aol.com.

Thanks, Ken.

steven@carsurvey.org: Below is an updated text added on 27th May 2003.

Due to the tremendous failure of the HT, there existed a surplus of aluminum blocks in auto wrecking yards. The engines could not be reliably rebuilt and the only worth that they had at the time was the "aluminum" which had an after-market melt-down value. GM sought to buy back many of these cores but was unfortuntely, outbid by its competitors. The blocks were subsequently melted down for industrial application. This caused a tremendous shortfall of blocks known as "float" or in common parlance, rebuildable blocks. Besides the core shortage, the HT with its unique free-standing wet liners and its tedious specifications was extremely difficult to "rebuild."

In the mid 1980's, the national and international demand for HT's was massive. GM thus kicked off a "remanufacturing" campaign and engaged the services of an independent engine remanufacturing concern. Following intensive study of repair, warranty repair data, performance, "hot testing" and other information in connection with the "infant" failures of the HT, GM and the remanufacturing concern forecast a considerable demand for HT's "per day."

Further impacting the remanufacturing campaign was the reality of foundry fallout and porosity problems. Accordingly, in the latter part of the 1980's the engine was placed on "national hold." GM and the independent concern made substantial gains in engineering fixes re: the design and process defects inherent in the HT. The remanufactured model was GM's biggest seller and circa 1989 was costing consumers upwards of $4,000 installed. The "daily", and I enunciate, "daily" demand for the blocks was a whopping 50 engines per day.

Those of you who contend you have seen "good HT's" may very well have purchased a vehicle with the remanufactured block. If the vehicle had the original engine, dollars to donuts the owner was fastidious about changing the oil and may have taken the advice of the savvy mechanics of the time who knew to periodically retorque the bolts in the engine and to check the bottom of the oilpan for the fatal "milkshake" (ethylene-glycol [anti-freeze], water, & gasoline) which was directly responsible for accelerated wear on "all" moving parts from main bearings to worm gears. Essentially, it turned the oil into "spit."

Accordingly, the elegant solution or remedy I am speaking of is to replace the OEM factory engine with the "remanufactured" HT which GM invested $$$$$$$$ in analysis, subsequent testing and re-engineering. But no one knows that because only a handful of people, litigated the matter. Simply replacing the failed HT with another factory manufactured engine would start the vicious cycle all over again. As I argued in my lawsuit, the engine was fatally "unmerchantable."

Gentlemen, this is just the tip of the iceberg. I prepared an extensive analysis of the engine and "ambushed" GM during my video-taped deposition with my findings. That frosted not only GM's expensive lawyers but its former chairman Roger Smith and others. Listen, GM's intention was "pure" in remanufacturing the little engine - it simply just blew it.

Further, no one is aware that the HT was not intended to power the big dreadnoughts, that is the vehicles with high curb weights, it was intended to power the "downsized" models that came out later. However, due to schedule slippage, it had no choice but to put them in the larger models. Gentlemen, that is why the poor weight-to-horsepower ratio and lethargic responsiveness. The fixes they employed were beneath the standards of quality engineering - that is - until the remanufactured unit was made available. The most damaging aspect of the HT was its metal-aluminum construction which caused the engine to expand and contract at different rates, and in connection with the infamous "milkshake" caused an extremely high incidence of infant engine failure.

And again, this is the tip of the iceberg. For those of you who may be in denial or are simply gainsayers, I have the video-taped deposition as well as my point-by-point detailed analysis of all reported and unreported problems associated with the design, dealing with infant failures, recalls, campaigns, service bulletins and so forth.

I really commiserate with the many fixes I see being exchanged and commend everyone on their resourcefulness and creativity with regard to your various approaches on attempting to apply fixes to the engine or chassis. I too loved my 1982 bustleback with its beautiful simulated rag-top, great mileage, and so forth. Unfortunately, I surrendered my vehicle post-litigation and had absolutely no desire to purchase another unit.